High self-sharpening concave-edge triangular ceramic abrasive and method of making same

Abstract

The application relates to the technical field of special ceramic product manufacturing, and particularly discloses a high-self-sharpening concave-edge triangular ceramic abrasive and a preparation method thereof. The ceramic abrasive comprises raw material pseudo-boehmite powder, a magnesium source, a silicon source, a titanium source, a dispersing agent and deionized water; the abrasive is in the form of a flat sheet as a whole, and the top view profile is triangular, wherein two side edges are inwardly concave arcs, and the third edge is a straight line. The asymmetric two-side inwardly concave arc combined with the straight line structure is adopted, and the design of the offset center of gravity enables the abrasive to generate directional stress concentration when being stressed, so that continuous micro-fracture self-sharpening is realized. Meanwhile, the offset center of gravity forms a strong polar moment in the electrostatic sand planting process, realizes the directional arrangement of the abrasive grains with high pass rate, and thus the grinding efficiency is remarkably improved, the grinding temperature is reduced, and the service life of the grinding tool is prolonged.

Description

Technical Field

[0001] This invention relates to the field of special ceramic product manufacturing technology, specifically to a high self-sharpening concave-edge triangular ceramic abrasive and its preparation method. Background Technology

[0002] With the rapid development of modern precision manufacturing and aerospace industries, more stringent requirements have been placed on the efficient and precision grinding of difficult-to-machine materials (such as high-temperature alloys, stainless steel, and titanium alloys). Ceramic abrasives, whose main component is microcrystalline alumina, have become the core grinding material for high-end coated abrasives (such as abrasive belts and abrasive discs) and bonded abrasives due to their extremely high hardness, excellent wear resistance, and special self-sharpening properties.

[0003] However, existing ceramic abrasives still face a series of technical bottlenecks that urgently need to be overcome in practical applications. Firstly, the ceramic abrasives commonly found on the market, prepared by traditional sintering followed by mechanical crushing, exhibit considerable randomness in shape, often consisting of blocky or irregular particles. This leads to uncontrollable cutting angles and poor chip removal during grinding, resulting in severe clogging between abrasive grains and burns on the workpiece surface. Secondly, in recent years, the industry has developed equilateral triangular ceramic abrasives using a sol-gel method combined with mold forming technology. While equilateral triangular abrasives have standardized the abrasive grain morphology to some extent, they still have the following significant drawbacks: (1) Limited number of independent grinding edges: Only three apex of the equilateral triangle participate in the main cutting, and there are fewer independent cutting edges on the cross section. Further improvement of cutting efficiency is limited by the structure.

[0004] (2) Low self-sharpening cycle efficiency: The three cutting edges of the equilateral triangle are subjected to excessively uniform and symmetrical forces, resulting in a balanced internal stress distribution of the abrasive grains during grinding, making it difficult to induce micro-fractures at the expected stress concentration points. Furthermore, excessive structural stability hinders the formation of the efficient cycle of "passivation → micro-fracture exposing new cutting edge → self-sharpening" of the abrasive grains, often leading to the overall dulling or large-scale fragmentation of the abrasive grains.

[0005] (3) Poor directional arrangement of electrostatic abrasive grains: The geometric center of an equilateral triangle is its centroid. In the electrostatic abrasive grain manufacturing process, because the centroid of the abrasive grains is in the center, the abrasive grains do not have a significant polarity deflection torque in the electric field, resulting in random orientation when falling into the substrate. This makes it impossible to achieve the ideal directional arrangement of "large end side against the substrate, tip facing outward for cutting," which seriously weakens the overall cutting sharpness of the abrasive. Based on the above, this invention proposes a high self-sharpening concave-edge triangular ceramic abrasive and its preparation method. Summary of the Invention

[0006] To address the technical problems of existing ceramic abrasives, such as insufficient grinding edge, poor self-sharpening properties of microfractures, easy clogging of chip removal, and poor directional arrangement of electrostatic sand, this invention proposes a high self-sharpening concave triangular ceramic abrasive and its preparation method.

[0007] In a first aspect, the present invention provides a highly self-sharpening concave-edge triangular ceramic abrasive, employing the following technical solution: A high self-sharpening concave-edge triangular ceramic abrasive comprises the following raw materials in parts by weight: 80-120 parts of pseudo-boehmite powder, 0.1-0.8 parts of magnesium source, 0.05-0.5 parts of silicon source, 0.01-0.1 parts of titanium source, 0.5-3 parts of dispersant, and 80-150 parts of deionized water; The abrasive is generally flat and sheet-like, with a triangular outline when viewed from above. Two of its sides are concave arcs, and the third side is a straight line.

[0008] Preferably, the radius of curvature R of the concave arc is 0.3-0.8 times the maximum width W of the abrasive, and the two concave arcs are symmetrical about the central perpendicular line to the straight side. This specific radius of curvature design ensures the sharpness of the cutting edge while avoiding the problem of insufficient mechanical strength and easy breakage of the cutting edge due to excessive curvature.

[0009] Preferably, the concave depth d of the concave arc is 10-30% of the maximum width W of the abrasive, and the thickness t of the abrasive is 0.05-0.5 mm.

[0010] Preferably, the abrasive has an aspect ratio L / W of 1.5-4, and its center of gravity is distributed in an off-center manner, where L is the length perpendicular to the straight side and W is the width of the straight side. This invention employs an off-center center of gravity design, causing the center of gravity to be significantly biased towards one side of the straight side, thus generating a very strong dipole directional torque in the electrostatic field.

[0011] Preferably, the magnesium source is magnesium oxide.

[0012] Preferably, the silicon source is silicon dioxide.

[0013] Preferably, the titanium source is titanium dioxide.

[0014] This invention effectively controls the size of α-Al2O3 microcrystals at the submicron level by introducing magnesium, silicon, and titanium sources as grain growth inhibitors and crystal phase regulators.

[0015] Preferably, the dispersant is selected from one or more combinations of citric acid, polyacrylic acid, or sodium hexametaphosphate.

[0016] Preferably, the cross-section of the abrasive has multiple independent grinding edges formed by concave arcs distributed along the thickness direction.

[0017] Secondly, the present invention provides a method for preparing a highly self-sharpening concave-edge triangular ceramic abrasive, employing the following technical solution: A method for preparing a highly self-sharpening concave-edge triangular ceramic abrasive includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium source, silicon source, titanium source, dispersant and deionized water are mixed and ball-milled to obtain a uniform sol; (2) Inject the sol into the pre-designed triangular mold. The top view of the mold cavity is a triangle with two concave arcs on the sides and one straight line on the side. The cavity depth is 0.3-1mm. (3) Dry the mold after injection molding at a temperature of 20-60℃ and a relative humidity of 40-80% for 12-72 hours to obtain a wet blank. During this process, the surface shrinkage during gel drying generates tensile stress. The stress is constrained along the straight edge of the mold cavity and released freely along the two curved edges, thus forming an inwardly concave cracked surface on the two sides and maintaining a straight shape on the straight edge. (4) After the wet blank is demolded, it is dried and sintered, and then shaped and acid-washed to obtain a high self-sharpening concave triangular ceramic abrasive.

[0018] Preferably, in step (1), the mixing ball milling parameters are: ball milling speed of 200-400 r / min, ball milling time of 12-16 h, ball milling medium of alumina balls with a diameter of 2-5 mm, ball-to-material ratio of 3-5:1, and standing for degassing for 1-2 h after ball milling.

[0019] Preferably, in step (4), the drying parameters are: temperature of 60-120℃ and time of 24-72h.

[0020] Preferably, in step (4), the sintering parameters are: in an air atmosphere, the temperature is raised to 1550-1750℃ at a heating rate of 2-5℃ / min, and sintered at that temperature for 2-4 hours.

[0021] Preferably, in step (4), the shaping parameters are: a double-roll crusher is used for deagglomeration, and the roller spacing is set to 1.1-1.5 times the thickness of the sintered abrasive body. This invention, by setting the roller spacing slightly larger than the thickness of a single layer of abrasive grains after sintering, ensures that the extrusion shear force provided by the rollers does not directly crush the abrasive grain body, but rather precisely acts on the fragile adhesion neck between the abrasive grains caused by high-temperature sintering. Under this specific stress state, the cleavage stress will naturally be released along the concave arc of the abrasive grain side, that is, at the weakest point of the structure where microcracks are easily initiated, thereby maintaining the integrity of the plate-like morphology of a single abrasive grain.

[0022] Preferably, in step (4), the pickling parameters are: washing with 5-10% dilute nitric acid or dilute hydrochloric acid at 40-60°C for 30-60 minutes, followed by washing with deionized water until neutral.

[0023] In summary, the present invention has the following beneficial effects: 1. The concave arc structure of the present invention forms multiple independent grinding edges. Compared with the symmetrical force of traditional straight-edged abrasives, the asymmetrical structure of the present invention can generate directional stress concentration when subjected to cutting resistance, which in turn matches the cleavage characteristics of microcrystalline ceramics, causing the abrasive grains to undergo nano / micron-level microfractures after passivation, continuously exposing new edges, greatly extending the sharpness cycle and improving grinding efficiency.

[0024] 2. This invention employs an asymmetrical centrifugal structure with "one straight edge and two concave edges," and limits the aspect ratio to 1.5-4, causing the abrasive grains' centrifugal center to be biased towards the straight edge. In an electrostatic field, the abrasive grains are subjected to force and flip, achieving stable embedding of the adhesive with the wider straight edge serving as a base. The concave intersections have a consistent directional arrangement with the tips facing outwards, resulting in a pass rate of over 96% and significantly improving the penetration capability of the abrasive belt.

[0025] 3. This invention employs a controllable drying and cracking process, utilizing the principle that the straight edges of the mold provide strong constraint and the curved edges provide free shrinkage space. The concave contour of the abrasive is formed through natural shrinkage guided by gel stress. This stress-guided shrinkage molding process avoids internal destructive damage and residual stress caused by traditional mechanical crushing, ensuring that the product is a completely sheet-like product without dead particles.

[0026] 4. The flat sheet-like structure combined with the concave arc side of the present invention allows adjacent abrasive grains to form an open chip removal channel on their sides after sand is applied, which has chip-holding and chip-removing performance, reduces frictional heat generation in the grinding zone, effectively reduces the risk of thermal damage to the workpiece surface, and extends the service life of the grinding wheel. Attached Figure Description

[0027] Figure 1 This is a top view schematic diagram of the high self-sharpening concave triangular ceramic abrasive of the present invention.

[0028] Figure 2 This is a comparison diagram of the high self-sharpening concave triangular ceramic abrasive of the present invention and the equilateral triangular abrasive of 3M. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the embodiments.

[0030] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0031] Among them, the pseudoboehmite powder: calculated as Al2O3, with a purity of 99.9% and a mesh size of 1250 mesh, model ZTL-CAH, brand Zhongtianli, was purchased from Yangzhou Zhongtianli New Material Co., Ltd.

[0032] Magnesium oxide has an effective component content of 99.9% and a mesh size of 2000 mesh; silicon dioxide has an effective component content of 99.99% and a mesh size of 3000 mesh; titanium dioxide has an effective component content of 99.95% and a mesh size of 6000 mesh. All of these products were purchased from Nangong Jiuxin New Material Technology Co., Ltd.

[0033] Examples 1-3 provide a high self-sharpening concave-edge triangular ceramic abrasive and its preparation method.

[0034] Example 1 A high self-sharpening concave triangular ceramic abrasive comprises the following raw materials in parts by weight: 100 parts of pseudoboehmite powder, 0.5 parts of magnesium oxide, 0.27 parts of silicon dioxide, 0.05 parts of titanium dioxide, 1.8 parts of citric acid, and 115 parts of deionized water. The abrasive is flat and flat, with a triangular outline when viewed from above. Two of its sides are concave arcs, and the third side is a straight line. The abrasive has a thickness t of 0.275 mm, an aspect ratio L / W of 2.75, and an offset center of gravity. The cross-section of the abrasive has multiple independent grinding edges formed by concave arcs along the thickness direction. The radius of curvature R of the concave arc is 0.5 times the maximum width W of the abrasive, and the two concave arcs are symmetrical about the center perpendicular line to the straight side. The concave depth d of the concave arc is 20% of the maximum width W of the abrasive.

[0035] A method for preparing a highly self-sharpening concave-edge triangular ceramic abrasive includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium oxide, silicon dioxide, titanium dioxide, citric acid and deionized water were mixed and ball-milled. The ball milling speed was controlled at 300 r / min and the ball milling time was 14 h. The ball milling media were alumina balls with a diameter of 3.5 mm and the ball-to-material ratio was 4:1. After ball milling, the mixture was allowed to stand for 1.5 h to remove bubbles and obtain a uniform sol. (2) Inject the sol into the pre-designed triangular mold. The top view of the mold cavity is a triangle with two concave arcs on the sides and one straight line on the side. The cavity depth is 0.7 mm. (3) The mold after injection molding is dried at a temperature of 40℃ and a relative humidity of 60% for 42 hours to obtain a wet blank; (4) After demolding the wet blank, it is dried at 90°C for 48 hours. Then, in an air atmosphere, the temperature is raised to 1650°C at a heating rate of 3.5°C / min and sintered for 3 hours. The abrasive is deagglomerated using a roller crusher. The roller spacing is set to 1.3 times the thickness of the sintered abrasive body. After shaping, it is washed with 7.5% dilute hydrochloric acid at 50°C for 45 minutes. Then, it is washed with deionized water until neutral. After vibrating and sieving, a high self-sharpening concave triangular ceramic abrasive is obtained.

[0036] Example 2 A high self-sharpening concave triangular ceramic abrasive comprises the following raw materials in parts by weight: 120 parts of pseudoboehmite powder, 0.8 parts of magnesium oxide, 0.5 parts of silicon dioxide, 0.1 parts of titanium dioxide, 3 parts of citric acid, and 150 parts of deionized water. The abrasive is flat and flat, with a triangular outline when viewed from above. Two of its sides are concave arcs, and the third side is a straight line. The abrasive has a thickness t of 0.5 mm, an aspect ratio L / W of 4, and an offset center of gravity. The cross-section of the abrasive has multiple independent grinding edges formed by concave arcs along the thickness direction. The radius of curvature R of the concave arc is 0.8 times the maximum width W of the abrasive, and the two concave arcs are symmetrical about the center perpendicular line to the straight side. The concave depth d of the concave arc is 30% of the maximum width W of the abrasive.

[0037] A method for preparing a highly self-sharpening concave-edge triangular ceramic abrasive includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium oxide, silicon dioxide, titanium dioxide, citric acid and deionized water were mixed and ball-milled. The ball milling speed was controlled at 400 r / min and the ball milling time was 12 h. The ball milling media were alumina balls with a diameter of 5 mm and the ball-to-material ratio was 3:1. After ball milling, the mixture was allowed to stand for 2 h to remove bubbles and obtain a uniform sol. (2) Inject the sol into the pre-designed triangular mold. The top view of the mold cavity is a triangle with two concave arcs on the sides and one straight line on the side. The cavity depth is 0.3 mm. (3) The mold after injection molding is dried at 20℃ and 80% relative humidity for 72 hours to obtain a wet blank; (4) After demolding the wet blank, it is dried at 120°C for 24 hours. Then, in an air atmosphere, the temperature is raised to 1750°C at a heating rate of 5°C / min and sintered for 2 hours. The abrasive is deagglomerated using a roller crusher. The roller spacing is set to 1.5 times the thickness of the sintered abrasive body. After shaping, it is washed with 10% dilute hydrochloric acid at 60°C for 30 minutes. Then, it is washed with deionized water until neutral. After vibrating and sieving, a high self-sharpening concave triangular ceramic abrasive is obtained.

[0038] Example 3 A high self-sharpening concave-triangular ceramic abrasive comprises the following raw materials in parts by weight: 80 parts of pseudoboehmite powder, 0.1 parts of magnesium oxide, 0.05 parts of silicon dioxide, 0.01 parts of titanium dioxide, 0.5 parts of citric acid, and 80 parts of deionized water. The abrasive is flat and flat, with a triangular outline when viewed from above. Two of its sides are concave arcs, and the third side is a straight line. The thickness t of the abrasive is 0.05 mm, the length-to-diameter ratio L / W is 1.5, the center of gravity is distributed in an off-center state, and the cross-section of the abrasive has multiple independent grinding edges formed by concave arcs distributed along the thickness direction. The radius of curvature R of the concave arc is 0.3 times the maximum width W of the abrasive, and the two concave arcs are symmetrical about the center perpendicular line to the straight side. The concave depth d of the concave arc is 10% of the maximum width W of the abrasive.

[0039] A method for preparing a highly self-sharpening concave-edge triangular ceramic abrasive includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium oxide, silicon dioxide, titanium dioxide, citric acid and deionized water were mixed and ball-milled. The ball milling speed was controlled at 200 r / min and the ball milling time was 16 h. The ball milling media were alumina balls with a diameter of 2 mm and the ball-to-material ratio was 5:1. After ball milling, the mixture was allowed to stand for 1 h to remove bubbles and obtain a uniform sol. (2) Inject the sol into the pre-designed triangular mold. The top view of the mold cavity is a triangle with two concave arcs on the sides and one straight line on the side. The cavity depth is 1mm. (3) The mold after injection molding is dried at a temperature of 60℃ and a relative humidity of 40% for 12 hours to obtain a wet blank; (4) After demolding the wet blank, it is dried at 60°C for 72 hours. Then, in an air atmosphere, it is heated to 1550°C at a heating rate of 2°C / min and sintered for 4 hours. The abrasive is deagglomerated using a roller crusher. The roller spacing is set to 1.1 times the thickness of the sintered abrasive body. After shaping, it is washed with 5% hydrochloric acid at 40°C for 60 minutes. Then, it is washed with deionized water until neutral. After vibrating and sieving, a high self-sharpening concave triangular ceramic abrasive is obtained.

[0040] To verify the comprehensive performance of the high self-sharpening concave-edge triangular ceramic abrasive provided by the present invention, comparative examples 1-8 were set up, wherein: Comparative Example 1 Comparative Example 1 is the same as Example 1, except that the mold cavity is replaced with a traditional equilateral triangular mold with a length-to-diameter ratio (L / W) of 0.86 and a perfectly centered center of gravity. Details are as follows: An equilateral triangular ceramic abrasive comprises the following raw materials in parts by weight: 100 parts of pseudoboehmite powder, 0.5 parts of magnesium oxide, 0.27 parts of silicon dioxide, 0.05 parts of titanium dioxide, 1.8 parts of citric acid, and 115 parts of deionized water. The abrasive material is flat and sheet-like, with an equilateral triangle shape when viewed from above. The thickness t of the abrasive is 0.275 mm, the length-to-diameter ratio L / W is 0.86, and the center of gravity is completely centered.

[0041] A method for preparing an equilateral triangular ceramic abrasive includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium oxide, silicon dioxide, titanium dioxide, citric acid and deionized water were mixed and ball-milled. The ball milling speed was controlled at 300 r / min and the ball milling time was 14 h. The ball milling media were alumina balls with a diameter of 3.5 mm and the ball-to-material ratio was 4:1. After ball milling, the mixture was allowed to stand for 1.5 h to remove bubbles and obtain a uniform sol. (2) Inject the sol into the pre-set triangular mold, and the top view of the mold cavity is an equilateral triangle; (3) The mold after injection molding is dried at a temperature of 40℃ and a relative humidity of 60% for 42 hours to obtain a wet blank; (4) After demolding the wet blank, it is dried at 90°C for 48 hours. Then, in an air atmosphere, the temperature is raised to 1650°C at a heating rate of 3.5°C / min and sintered for 3 hours. The agglomerates are deagglomerated using a roller crusher. The roller spacing is set to 1.3 times the thickness of the sintered abrasive body. After shaping, it is washed with 7.5% dilute hydrochloric acid at 50°C for 45 minutes. Then, it is washed with deionized water until neutral. After vibrating and sieving, equilateral triangular ceramic abrasive is obtained.

[0042] Comparative Example 2 Comparative Example 2 is the same as Example 1, except that the forming method is changed to a conventional mechanical crushing method after sintering. Details are as follows: A ceramic abrasive comprises the following raw materials in parts by weight: 100 parts of boehmite powder, 0.5 parts of magnesium oxide, 0.27 parts of silicon dioxide, 0.05 parts of titanium dioxide, 1.8 parts of citric acid, and 115 parts of deionized water. The abrasive material is generally in the form of irregular blocks or granules.

[0043] A method for preparing a highly self-sharpening concave-edge triangular ceramic abrasive includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium oxide, silicon dioxide, titanium dioxide, citric acid and deionized water were mixed and ball-milled. The ball milling speed was controlled at 300 r / min and the ball milling time was 14 h. The ball milling media were alumina balls with a diameter of 3.5 mm and the ball-to-material ratio was 4:1. After ball milling, the mixture was allowed to stand for 1.5 h to remove bubbles and obtain a uniform sol. (2) The sol was dried at 40°C for 30 hours to obtain a wet blank; (3) After demolding the wet blank, dry it at 90°C for 48 hours. In an air atmosphere, heat it to 1650°C at a heating rate of 3.5°C / min and hold it for sintering for 3 hours. After cooling, use a jaw crusher for mechanical crushing. Set the main shaft speed of the jaw crusher to 280 r / min and the discharge port gap to 2 mm. After crushing, wash it with 7.5% dilute hydrochloric acid at 50°C for 45 minutes. Then wash it with deionized water until neutral. Vibrate and screen to obtain ceramic abrasive.

[0044] Comparative Example 3 Comparative Example 3 is the same as Example 1, except that the relative humidity in step (3) of the drying stage is reduced to 20% for rapid dehydration and drying. Specifically: A high self-sharpening concave triangular ceramic abrasive comprises the following raw materials in parts by weight: 100 parts of pseudoboehmite powder, 0.5 parts of magnesium oxide, 0.27 parts of silicon dioxide, 0.05 parts of titanium dioxide, 1.8 parts of citric acid, and 115 parts of deionized water. The abrasive is flat and flat, with a triangular outline when viewed from above. Two of its sides are concave arcs, and the third side is a straight line. The abrasive has a thickness t of 0.275 mm, an aspect ratio L / W of 2.75, and an offset center of gravity. The cross-section of the abrasive has multiple independent grinding edges formed by concave arcs along the thickness direction. The radius of curvature R of the concave arc is 0.5 times the maximum width W of the abrasive, and the two concave arcs are symmetrical about the center perpendicular line to the straight side. The concave depth d of the concave arc is 20% of the maximum width W of the abrasive.

[0045] A method for preparing a highly self-sharpening concave-edge triangular ceramic abrasive includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium oxide, silicon dioxide, titanium dioxide, citric acid and deionized water were mixed and ball-milled. The ball milling speed was controlled at 300 r / min and the ball milling time was 14 h. The ball milling media were alumina balls with a diameter of 3.5 mm and the ball-to-material ratio was 4:1. After ball milling, the mixture was allowed to stand for 1.5 h to remove bubbles and obtain a uniform sol. (2) Inject the sol into the pre-designed triangular mold. The top view of the mold cavity is a triangle with two concave arcs on the sides and one straight line on the side. The cavity depth is 0.7 mm. (3) The mold after injection molding is dried at a temperature of 40℃ and a relative humidity of 60% for 42 hours to obtain a wet blank; (4) After demolding the wet blank, it is dried at 90°C for 48 hours. Then, in an air atmosphere, the temperature is raised to 1650°C at a heating rate of 3.5°C / min and sintered for 3 hours. The abrasive is deagglomerated using a roller crusher. The roller spacing is set to 1.3 times the thickness of the sintered abrasive body. After shaping, it is washed with 7.5% dilute hydrochloric acid at 50°C for 45 minutes. Then, it is washed with deionized water until neutral. After vibrating and sieving, a high self-sharpening concave triangular ceramic abrasive is obtained.

[0046] Comparative Example 4 Comparative Example 4 is the same as Example 1, except that the mold size is adjusted and the length-to-diameter ratio (L / W) of the abrasive is set to 1. Specifically: A high self-sharpening concave triangular ceramic abrasive comprises the following raw materials in parts by weight: 100 parts of pseudoboehmite powder, 0.5 parts of magnesium oxide, 0.27 parts of silicon dioxide, 0.05 parts of titanium dioxide, 1.8 parts of citric acid, and 115 parts of deionized water. The abrasive is flat and flat, with a triangular outline when viewed from above. Two of its sides are concave arcs, and the third side is a straight line. The thickness t of the abrasive is 0.275 mm, the length-to-diameter ratio L / W is 1, the center of gravity is distributed in an off-center state, and the cross-section of the abrasive has multiple independent grinding edges formed by concave arcs distributed along the thickness direction. The radius of curvature R of the concave arc is 0.5 times the maximum width W of the abrasive, and the two concave arcs are symmetrical about the center perpendicular line to the straight side. The concave depth d of the concave arc is 20% of the maximum width W of the abrasive.

[0047] A method for preparing a highly self-sharpening concave-edge triangular ceramic abrasive includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium oxide, silicon dioxide, titanium dioxide, citric acid and deionized water were mixed and ball-milled. The ball milling speed was controlled at 300 r / min and the ball milling time was 14 h. The ball milling media were alumina balls with a diameter of 3.5 mm and the ball-to-material ratio was 4:1. After ball milling, the mixture was allowed to stand for 1.5 h to remove bubbles and obtain a uniform sol. (2) Inject the sol into the pre-designed triangular mold. The top view of the mold cavity is a triangle with two concave arcs on the sides and one straight line on the side. The cavity depth is 0.7 mm. (3) The mold after injection molding is dried at a temperature of 40℃ and a relative humidity of 60% for 42 hours to obtain a wet blank; (4) After demolding the wet blank, it is dried at 90°C for 48 hours. Then, in an air atmosphere, the temperature is raised to 1650°C at a heating rate of 3.5°C / min and sintered for 3 hours. The abrasive is deagglomerated using a roller crusher. The roller spacing is set to 1.3 times the thickness of the sintered abrasive body. After shaping, it is washed with 7.5% dilute hydrochloric acid at 50°C for 45 minutes. Then, it is washed with deionized water until neutral. After vibrating and sieving, a high self-sharpening concave triangular ceramic abrasive is obtained.

[0048] Comparative Example 5 Comparative Example 5 is the same as Example 1, except that the mold curvature is modified, and the radius of curvature R is reduced and set to 0.1W. Specifically: A high self-sharpening concave triangular ceramic abrasive comprises the following raw materials in parts by weight: 100 parts of pseudoboehmite powder, 0.5 parts of magnesium oxide, 0.27 parts of silicon dioxide, 0.05 parts of titanium dioxide, 1.8 parts of citric acid, and 115 parts of deionized water. The abrasive is flat and flat, with a triangular outline when viewed from above. Two of its sides are concave arcs, and the third side is a straight line. The abrasive has a thickness t of 0.275 mm, an aspect ratio L / W of 2.75, and an offset center of gravity. The cross-section of the abrasive has multiple independent grinding edges formed by concave arcs along the thickness direction. The radius of curvature R of the concave arc is 0.1 times the maximum width W of the abrasive, and the two concave arcs are symmetrical about the center perpendicular line to the straight side. The concave depth d of the concave arc is 20% of the maximum width W of the abrasive.

[0049] A method for preparing a highly self-sharpening concave-edge triangular ceramic abrasive includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium oxide, silicon dioxide, titanium dioxide, citric acid and deionized water were mixed and ball-milled. The ball milling speed was controlled at 300 r / min and the ball milling time was 14 h. The ball milling media were alumina balls with a diameter of 3.5 mm and the ball-to-material ratio was 4:1. After ball milling, the mixture was allowed to stand for 1.5 h to remove bubbles and obtain a uniform sol. (2) Inject the sol into the pre-designed triangular mold. The top view of the mold cavity is a triangle with two concave arcs on the sides and one straight line on the side. The cavity depth is 0.7 mm. (3) The mold after injection molding is dried at a temperature of 40℃ and a relative humidity of 60% for 42 hours to obtain a wet blank; (4) After demolding the wet blank, it is dried at 90°C for 48 hours. Then, in an air atmosphere, the temperature is raised to 1650°C at a heating rate of 3.5°C / min and sintered for 3 hours. The abrasive is deagglomerated using a roller crusher. The roller spacing is set to 1.3 times the thickness of the sintered abrasive body. After shaping, it is washed with 7.5% dilute hydrochloric acid at 50°C for 45 minutes. Then, it is washed with deionized water until neutral. After vibrating and sieving, a high self-sharpening concave triangular ceramic abrasive is obtained.

[0050] Comparative Example 6 Comparative Example 6 is the same as Example 1, except that the thickness t of the abrasive is increased to 0.8 mm. Details are as follows: A high self-sharpening concave triangular ceramic abrasive comprises the following raw materials in parts by weight: 100 parts of pseudoboehmite powder, 0.5 parts of magnesium oxide, 0.27 parts of silicon dioxide, 0.05 parts of titanium dioxide, 1.8 parts of citric acid, and 115 parts of deionized water. The abrasive is flat and flat, with a triangular outline when viewed from above. Two of its sides are concave arcs, and the third side is a straight line. The abrasive has a thickness t of 0.8 mm, an aspect ratio L / W of 2.75, and an offset center of gravity. The cross-section of the abrasive has multiple independent grinding edges formed by concave arcs along the thickness direction. The radius of curvature R of the concave arc is 0.5 times the maximum width W of the abrasive, and the two concave arcs are symmetrical about the center perpendicular line to the straight side. The concave depth d of the concave arc is 20% of the maximum width W of the abrasive.

[0051] A method for preparing a highly self-sharpening concave-edge triangular ceramic abrasive includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium oxide, silicon dioxide, titanium dioxide, citric acid and deionized water were mixed and ball-milled. The ball milling speed was controlled at 300 r / min and the ball milling time was 14 h. The ball milling media were alumina balls with a diameter of 3.5 mm and the ball-to-material ratio was 4:1. After ball milling, the mixture was allowed to stand for 1.5 h to remove bubbles and obtain a uniform sol. (2) Inject the sol into the pre-designed triangular mold. The top view of the mold cavity is a triangle with two concave arcs on the sides and one straight line on the side. The cavity depth is 0.7 mm. (3) The mold after injection molding is dried at a temperature of 40℃ and a relative humidity of 60% for 42 hours to obtain a wet blank; (4) After demolding the wet blank, it is dried at 90°C for 48 hours. Then, in an air atmosphere, the temperature is raised to 1650°C at a heating rate of 3.5°C / min and sintered for 3 hours. The abrasive is deagglomerated using a roller crusher. The roller spacing is set to 1.3 times the thickness of the sintered abrasive body. After shaping, it is washed with 7.5% dilute hydrochloric acid at 50°C for 45 minutes. Then, it is washed with deionized water until neutral. After vibrating and sieving, a high self-sharpening concave triangular ceramic abrasive is obtained.

[0052] Comparative Example 7 Comparative Example 7 is the same as Example 1, except that a layer of release lubricant is pre-coated onto the inner wall of the straight edge of the mold. Specifically: A high self-sharpening concave triangular ceramic abrasive comprises the following raw materials in parts by weight: 100 parts of pseudoboehmite powder, 0.5 parts of magnesium oxide, 0.27 parts of silicon dioxide, 0.05 parts of titanium dioxide, 1.8 parts of citric acid, and 115 parts of deionized water. The abrasive is flat and flat, with a triangular outline when viewed from above. Two of its sides are concave arcs, and the third side is a straight line. The abrasive has a thickness t of 0.275 mm, an aspect ratio L / W of 2.75, and an offset center of gravity. The cross-section of the abrasive has multiple independent grinding edges formed by concave arcs along the thickness direction. The radius of curvature R of the concave arc is 0.5 times the maximum width W of the abrasive, and the two concave arcs are symmetrical about the center perpendicular line to the straight side. The concave depth d of the concave arc is 20% of the maximum width W of the abrasive.

[0053] A method for preparing a highly self-sharpening concave-edge triangular ceramic abrasive includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium oxide, silicon dioxide, titanium dioxide, citric acid and deionized water were mixed and ball-milled. The ball milling speed was controlled at 300 r / min and the ball milling time was 14 h. The ball milling media were alumina balls with a diameter of 3.5 mm and the ball-to-material ratio was 4:1. After ball milling, the mixture was allowed to stand for 1.5 h to remove bubbles and obtain a uniform sol. (2) The sol is injected into the pre-designed triangular mold. The top view of the mold cavity is a triangle with two concave arcs and one straight line. The cavity depth is 0.7 mm, and the inner wall of the straight edge of the mold cavity is pre-coated with a layer of release lubricant. (3) The mold after injection molding is dried at a temperature of 40℃ and a relative humidity of 60% for 42 hours to obtain a wet blank; (4) After demolding the wet blank, it is dried at 90°C for 48 hours. Then, in an air atmosphere, the temperature is raised to 1650°C at a heating rate of 3.5°C / min and sintered for 3 hours. The abrasive is deagglomerated using a roller crusher. The roller spacing is set to 1.3 times the thickness of the sintered abrasive body. After shaping, it is washed with 7.5% dilute hydrochloric acid at 50°C for 45 minutes. Then, it is washed with deionized water until neutral. After vibrating and sieving, a high self-sharpening concave triangular ceramic abrasive is obtained.

[0054] Comparative Example 8 Comparative Example 8 is the same as Example 1, except that the amount of dispersant citric acid is increased to 5 parts. Details are as follows: A high self-sharpening concave-edge triangular ceramic abrasive comprises the following raw materials in parts by weight: 100 parts of pseudoboehmite powder, 0.5 parts of magnesium oxide, 0.27 parts of silicon dioxide, 0.05 parts of titanium dioxide, 5 parts of citric acid, and 115 parts of deionized water. The abrasive is flat and flat, with a triangular outline when viewed from above. Two of its sides are concave arcs, and the third side is a straight line. The abrasive has a thickness t of 0.275 mm, an aspect ratio L / W of 2.75, and an offset center of gravity. The cross-section of the abrasive has multiple independent grinding edges formed by concave arcs along the thickness direction. The radius of curvature R of the concave arc is 0.5 times the maximum width W of the abrasive, and the two concave arcs are symmetrical about the center perpendicular line to the straight side. The concave depth d of the concave arc is 20% of the maximum width W of the abrasive.

[0055] A method for preparing a highly self-sharpening concave-edge triangular ceramic abrasive includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium oxide, silicon dioxide, titanium dioxide, citric acid and deionized water were mixed and ball-milled. The ball milling speed was controlled at 300 r / min and the ball milling time was 14 h. The ball milling media were alumina balls with a diameter of 3.5 mm and the ball-to-material ratio was 4:1. After ball milling, the mixture was allowed to stand for 1.5 h to remove bubbles and obtain a uniform sol. (2) Inject the sol into the pre-designed triangular mold. The top view of the mold cavity is a triangle with two concave arcs on the sides and one straight line on the side. The cavity depth is 0.7 mm. (3) The mold after injection molding is dried at a temperature of 40℃ and a relative humidity of 60% for 42 hours to obtain a wet blank; (4) After demolding the wet blank, it is dried at 90°C for 48 hours. Then, in an air atmosphere, the temperature is raised to 1650°C at a heating rate of 3.5°C / min and sintered for 3 hours. The abrasive is deagglomerated using a roller crusher. The roller spacing is set to 1.3 times the thickness of the sintered abrasive body. After shaping, it is washed with 7.5% dilute hydrochloric acid at 50°C for 45 minutes. Then, it is washed with deionized water until neutral. After vibrating and sieving, a high self-sharpening concave triangular ceramic abrasive is obtained.

[0056] Performance testing The comprehensive performance of the high self-sharpening concave-edge triangular ceramic abrasives prepared in Examples 1-3 and Comparative Examples 1-8 was tested respectively.

[0057] Test method: Using an epoxy resin / phenolic resin double-layer adhesive, the above-mentioned abrasive particles were implanted into a polyester fabric substrate under a 30kV high voltage electrostatic condition and cured to form an annular abrasive belt.

[0058] 1. Grinding ratio and grinding temperature test: A constant pressure belt grinding test machine was used, with 304 stainless steel as the workpiece (pressure set at 100N, linear speed at 25m / s), and grinding for 15 minutes. The grinding ratio was calculated as: workpiece weight removed / belt wear weight. The highest temperature in the grinding zone was recorded in real time using an infrared thermal imager.

[0059] 2. Directional sand planting qualification rate test: The surface of the sand belt is scanned using a super depth-of-field three-dimensional microscope, and the percentage of abrasive grains with "straight edges adhering to the substrate and tips facing outwards, and the angle between the longitudinal axis and the substrate normal is <15 degrees" per unit area is counted to the total number of sand-planted abrasive grains.

[0060] The test results are shown in Table 1: Table 1: As shown in Table 1, the high self-sharpening concave-edge triangular ceramic abrasives prepared in Examples 1-3 of this invention have a grinding ratio of over 12.8, the highest temperature in the grinding zone is effectively controlled below 320℃, and the directional sand planting qualification rate is over 95%. Their comprehensive performance is significantly better than that of Comparative Examples 1-8.

[0061] As shown in Example 1 and Comparative Example 1, the asymmetric concave triangular structure with an offset center of gravity significantly improves the directional abrasive loading success rate, reduces grinding temperature, and increases the grinding ratio compared to the traditional equilateral triangular structure. The structural physical mechanism is as follows: the asymmetric stress-bearing edge promotes directional stress concentration, achieving stable micro-fracture and exposing new cutting edges; while the offset center of gravity generates an effective deflection torque in the electrostatic field, promoting excellent directional alignment of abrasive grains during the abrasive loading stage.

[0062] As can be seen from Example 1 and Comparative Example 2, the use of sol-gel injection molding and shrinkage stress forming process can obtain ceramic abrasives with regular morphology and controlled cutting angles compared with conventional mechanical crushing method after sintering. This effectively avoids workpiece grinding heat caused by poor chip removal and shows significant technical progress in grinding ratio and sand loading qualification rate.

[0063] As shown in Example 1 and Comparative Example 3, controlling the relative humidity to 40-80% during the drying process is crucial for the orderly release of internal stress in the abrasive grains. Too low a relative humidity (e.g., 20%) will cause the gel to dehydrate too quickly, generating residual stress microcracks inside the abrasive grains. This leads to macroscopic fracture failure of the abrasive grains in the early stages of cutting stress, reducing the service life of the abrasive tool.

[0064] As can be seen from Example 1 and Comparative Example 4, setting the abrasive's length-to-diameter ratio (L / W) within the range of 1.5-4 can ensure effective offset of the center of gravity. A length-to-diameter ratio that is too small (e.g., L / W = 1) will result in insufficient offset of the abrasive's center of gravity, weakening the polar torque during electrostatic abrasive application, causing random abrasive grain arrangement, and leading to a decrease in the pass rate.

[0065] As can be seen from Example 1 and Comparative Example 5, limiting the radius of curvature R of the concave arc to 0.3-0.8W can effectively balance the sharpness and mechanical strength of the cutting edge. If the radius of curvature is too small (e.g., 0.1W), the cutting edge will be too sharp and thin, with insufficient mechanical strength, and the tip is prone to breakage during grinding, thus weakening the self-sharpening cycle performance.

[0066] As shown in Example 1 and Comparative Example 6, controlling the abrasive thickness t within the range of 0.05-0.5 mm is beneficial for inducing microfracture behavior. Excessive thickness (such as 0.8 mm) will result in excessively high cross-sectional stiffness of the abrasive grains. After the abrasive grains are passivated, they are difficult to undergo microfracture under stress, resulting in the abrasive grains exhibiting overall passivation characteristics, and grinding resistance and frictional heat will increase accordingly.

[0067] As can be seen from Example 1 and Comparative Example 7, the strong physical constraint of the straight edge of the mold is the driving basis for the formation of the concave arc contour by gel shrinkage. Pre-coating the straight edge with a release agent will cause the constraint force of the straight boundary to fail, thereby hindering the effective shrinkage of the concave arc, making it impossible for the abrasive grains to form a sufficiently wide chip removal channel, which in turn leads to an increase in the temperature of the grinding area.

[0068] As can be seen from Example 1 and Comparative Example 8, the amount of dispersant must be strictly controlled between 0.5 and 3 parts. If an excessive amount of dispersant is added (e.g., 5 parts), the excessive volatilization of organic matter during high-temperature sintering will lead to the formation of excessive micropores inside the ceramic microcrystals, which will damage the compactness of the matrix, significantly reduce the intrinsic compressive strength of the abrasive, and cause abnormal breakage.

[0069] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A high self-sharpening concave-edge triangular ceramic abrasive, characterized in that, The raw materials include the following parts by weight: 80-120 parts of boehmite powder, 0.1-0.8 parts of magnesium source, 0.05-0.5 parts of silicon source, 0.01-0.1 parts of titanium source, 0.5-3 parts of dispersant, and 80-150 parts of deionized water; The abrasive is generally flat and sheet-like, with a triangular outline when viewed from above. Two of its sides are concave arcs, and the third side is a straight line.

2. The high self-sharpening concave-edge triangular ceramic abrasive according to claim 1, characterized in that, The radius of curvature R of the concave arc is 0.3-0.8 times the maximum width W of the abrasive, and the two concave arcs are symmetrical about the center perpendicular line to the straight side.

3. The high self-sharpening concave-edge triangular ceramic abrasive according to claim 1, characterized in that, The concave depth d of the concave arc is 10-30% of the maximum width W of the abrasive.

4. The high self-sharpening concave-edge triangular ceramic abrasive according to claim 1, characterized in that, The abrasive has a thickness t of 0.05-0.5 mm and an aspect ratio L / W of 1.5-4, where L is the length perpendicular to the straight side and W is the width of the straight side.

5. The high self-sharpening concave-edge triangular ceramic abrasive according to claim 1, characterized in that, The magnesium source is magnesium oxide.

6. The high self-sharpening concave-edge triangular ceramic abrasive according to claim 1, characterized in that, The silicon source is silicon dioxide.

7. The high self-sharpening concave-edge triangular ceramic abrasive according to claim 1, characterized in that, The titanium source is titanium dioxide.

8. The high self-sharpening concave-edge triangular ceramic abrasive according to claim 1, characterized in that, The dispersant is selected from one or more combinations of citric acid, polyacrylic acid, or sodium hexametaphosphate.

9. A method for preparing a high self-sharpening concave-edge triangular ceramic abrasive according to any one of claims 1-8, characterized in that, Includes the following steps: (1) By weight, the pseudoboehmite powder, magnesium source, silicon source, titanium source, dispersant and deionized water are mixed and ball-milled to obtain a uniform sol; (2) Inject the sol into the pre-designed triangular mold. The top view of the mold cavity is a triangle with two concave arcs on the sides and one straight line on the side. The cavity depth is 0.3-1mm. (3) Dry the mold after injection molding at a temperature of 20-60℃ and a relative humidity of 40-80% for 12-72 hours to obtain a wet blank; (4) After the wet blank is demolded, it is dried and sintered, and then shaped and acid-washed to obtain a high self-sharpening concave triangular ceramic abrasive.

10. The method for preparing the high self-sharpening concave-edge triangular ceramic abrasive according to claim 9, characterized in that, In step (4), the sintering parameters are: in an air atmosphere, the temperature is raised to 1550-1750℃ at a heating rate of 2-5℃ / min, and sintered at that temperature for 2-4 hours.

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