Method for preparing ceramic bond through solution heat preservation and superhard grinding tool

Abstract

The invention provides a method for preparing a ceramic bond through solution heat preservation and a superhard grinding tool. The ceramic bonding agent prepared through a solution heat preservation method is fine in powder granularity and low in sintering temperature and contains a certain amount of crystals, the bonding agent has high impact resistance and self-sharpening performance due to existence of the crystals, and the prepared superhard ceramic grinding tool has the performance of high strength and good sharpness. The method has the advantages of short binding agent preparation period, low equipment investment cost, simplicity in operation and the like. The preparation method of the ceramic bond provided by the invention is not reported.

Description

Technical Field

[0001] The invention belongs to the technical field of superhard binders, and relates to a ceramic binder suitable for the superhard abrasive tool industry, a preparation method and an application thereof, in particular to a method for preparing a ceramic binder by heat preservation of a solution and a superhard abrasive tool. Background Art

[0002] The binder required for existing superhard ceramic abrasive tools often uses ceramic binder powder that has been melted into a melt at high temperature, because the melted ceramic binder has a better wetting effect on the abrasive. For the preparation of traditional ceramic binders, the preparation of the binder requires high-temperature melting, thereby improving the performance of the binder, enhancing the wetting effect of the binder on the abrasive, and ultimately improving the performance of the abrasive tool. This is common technical knowledge in the field, but the melting process of the binder preparation consumes a lot of energy and resources. Summary of the invention

[0003] The currently known methods for preparing ceramic binders are mainly smelting methods. The present invention adopts a new technical idea, overcomes the technical prejudice of the prior art that the preparation of ceramic binders requires ultra-high temperature (greater than 1000°C) smelting, and prepares ceramic binders for the first time by solution insulation method, which has not been reported. Solution insulation method is a wet chemical synthesis method, which prepares these raw materials into a solution, reacts at a certain heat treatment temperature, and the obtained powder is fluffy and fragile with ultra-fine particles and a lower melting point; this method is carried out in a solution, and can achieve uniform mixing at the molecular atomic level; the synthesis temperature is low and the time is short; therefore, the present invention has a good prospect in the preparation of ceramic binder powder.

[0004] The present invention adopts the following technical scheme.

[0005] A method for preparing a ceramic binder by heat preservation of a solution comprises the following steps: heat preservation treatment of a liquid containing metal nitrate, a water-soluble additive, tetraethyl orthosilicate and boric acid to obtain a powder; and grinding the powder to obtain a ceramic binder.

[0006] The invention discloses a method for preparing a superhard abrasive tool, comprising the following steps: subjecting a liquid containing metal nitrate, a water-soluble additive, tetraethyl orthosilicate and boric acid to heat preservation treatment to obtain a powder; grinding the powder to obtain a ceramic binder; and mixing the abrasive, the ceramic binder and a resin liquid, forming, drying and sintering the mixture to obtain a superhard abrasive tool.

[0007] In the present invention, the metal nitrate includes one or more of yttrium nitrate, aluminum nitrate, zirconium nitrate and zinc nitrate, and preferably, the metal nitrate contains zirconium nitrate; the water-soluble additive includes one or more of citric acid, sucrose, urea and polyethylene glycol.

[0008] In the present invention, the molar ratio of the water-soluble additive to all metal ions in the metal nitrate is (0.1-3.5):1, preferably (0.1-2):1, and more preferably (0.1-0.5):1.

[0009] In the present invention, the amount of tetraethyl orthosilicate added is 15-30% of the total weight of the metal nitrate, and the amount of boric acid added is 30-50% of the total weight of the metal nitrate.

[0010] In the present invention, the pH of the system containing metal nitrate and water-soluble additive is maintained at 2-4, and then ethyl orthosilicate and boric acid are added to obtain a liquid.

[0011] In the present invention, the heat preservation treatment is to keep the temperature at 250-500°C for 0.5-8h in an oxygen-containing gas; specifically, the liquid is placed in an air or oxygen environment at 250-500°C for 0.5-8h, preferably 350-450°C for 1-5h. The present invention adopts a treatment temperature below 500°C, and the obtained ceramic binder has better application performance.

[0012] In the present invention, the powder is ball-milled to obtain a ceramic binder; preferably, the ball milling is wet ball milling, and the weight ratio of the material, the ball and the alcohol in the ball milling is 1: (1-3): (0.1-2), preferably 1: (1-2): (0.2-1); the ball milling time is 0.5-24h, preferably 3-12h, and the ball milling speed is 100-5000r / min, preferably 300-2500r / min; after ball milling, the material is dried and sieved to obtain a material with a particle size of 1-3μm as the ceramic binder of the present invention.

[0013] The invention discloses the application of the ceramic binder in preparing superhard abrasive tools, such as preparing CBN abrasive tools. The abrasive tools have lower sintering temperature, strong abrasive holding force, long service life, and the preparation method is simple.

[0014] The invention discloses a superhard abrasive tool, comprising the ceramic binder and abrasive.

[0015] Preferably, the abrasive includes CBN abrasive; the resin liquid is a common commercially available phenolic resin liquid, so that the abrasive binder is mixed and formed.

[0016] Preferably, the weight ratio of the abrasive, the ceramic binder and the resin liquid is (65-85):(5-25):(3-5), preferably (75-85):(10-20):(4-5), such as 80:15:5.

[0017] The invention discloses the application of the superhard abrasive tool, such as CBN abrasive tool, in the inner circle machining of a compressor.

[0018] The invention discloses a method for machining the inner circle of a compressor, comprising the following steps: machining the inner circle of the compressor by using the superhard abrasive tool to complete the machining of the inner circle of the compressor.

[0019] The object of the present invention is to provide a ceramic binder which has better performance than conventional ceramic binders, is fluffy and brittle, has ultrafine particles and a lower melting point.

[0020] Compared with the prior art, the ceramic binder and the preparation method thereof provided by the present invention have the following advantages: the ceramic binder prepared by the solution heat preservation method provided by the present invention is easier to break and has a finer particle size than the conventional smelting ceramic binder, does not require smelting, has a simple preparation method, and reacts more thoroughly and disperses more evenly through molecular and atomic level mixing in the solution. When preparing into a ceramic abrasive tool, the sintering temperature is relatively low, and after sintering, more nanocrystals can be generated in the glass under certain conditions, which has the effect of improving the sharpness of the abrasive tool.

[0021] The CBN grinding tool provided by the invention has high sharpness and good toughness; the preparation method of the CBN grinding tool provided by the invention has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention provides a process roadmap for preparing the ceramic binder.

[0023] Figure 2 This is a photograph of the ceramic binder of the present invention before ball milling.

[0024] Figure 3 This is a photo of the comparative example ceramic bond before ball milling.

[0025] Figure 4 This is a scanning electron photograph of the ceramic CBN grinding tool according to Example 2 of the present invention. DETAILED DESCRIPTION

[0026] The embodiments of the present invention will be described in detail below in conjunction with the embodiments and examples, but those skilled in the art will appreciate that the following embodiments and examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. If no specific conditions are specified, proceed according to conventional conditions or conditions recommended by the manufacturer. The raw materials involved in the present invention are all commercially available products, available on the market, and meet the conventional application requirements of superhard abrasives. Those skilled in the art can obtain applicable raw materials without creative work.

[0027] The invention provides a ceramic binder, which is prepared by a solution heat preservation method, comprising the following steps: 1. preparing a solution from nitrates such as yttrium nitrate, aluminum nitrate, zirconium nitrate, zinc nitrate and water-soluble additives such as citric acid, sucrose and the like, with water as a solvent; 2. adjusting the pH value within a certain range by using ammonia water; 3. adding boric acid and ethyl orthosilicate into the solution and mixing and stirring; and finally subjecting the obtained liquid to heat preservation treatment in a muffle furnace, ball milling and sieving to obtain the ceramic binder.

[0028] The present invention discloses a method for preparing a ceramic binder by heat preservation of a solution, comprising the following steps: (1) Raw material M x (NO3) y Dissolve in water, stir in a water bath at 50-100°C until the solution is clear, that is, prepare a metal salt solution with a total metal ion concentration (the sum of the concentrations of all metals) of 0.3-5 mol / L, wherein M is one or more of Y, Al, Zr or Zn, 0<x, y≤3; (2) adding water-soluble additives such as citric acid, sucrose, etc. to the above solution; (3) adding ammonia water to adjust the pH to 2-4, adding ethyl orthosilicate and boric acid, and continuing to heat in a water bath at 50-110° C. with stirring for 0.5-3 h, preferably at 60-80° C. with stirring for 1-2 h, to obtain a liquid; (4) placing the liquid obtained in step (3) in a device for heat preservation to obtain a powder; (5) The powder obtained in step (4) is wet ball-milled, dried and sieved to obtain a ceramic binder.

[0029] In the above technical solution, the water-soluble additive is selected from one or more of citric acid, sucrose, urea, polyethylene glycol, etc., preferably citric acid. x (NO3) y The total metal molar ratio is 0.1-3.5, preferably 0.15-0.4; the amount of tetraethyl orthosilicate added is 15-30% of the total weight of the metal nitrate, and the amount of boric acid added is 30-50% of the total weight of the metal nitrate. Preferably, the amount of tetraethyl orthosilicate added is 20-28% of the total weight of the metal nitrate, and the amount of boric acid added is 35-40% of the total weight of the metal nitrate.

[0030] In the above technical solution, the equipment is a muffle furnace or a tubular furnace; the insulation is to place the liquid in an air or oxygen environment at a temperature of 250-500°C for 0.5-8h, preferably 350-420°C for 1-2h.

[0031] In the above technical scheme, during wet ball milling, the weight ratio of material, ball and alcohol is 1: (1-3): (0.1-2), preferably 1: (1-2): (0.2-1), such as 1: 1.5: 0.5, 1: 1: 0.4; the ball milling time is 0.5-24h, preferably 3-5h, the ball milling speed is 500-1000r / min, and after ball milling, the material is dried and sieved to obtain a particle size of 1-3μm as the ceramic binder of the present invention.

[0032] In the present invention, a ceramic binder is prepared by a solution heat preservation method, and the solution is mixed evenly. After the effects of heat preservation reaction, the obtained powder is fluffy and has ultrafine particles. The prepared ceramic abrasive tool has a lower sintering temperature. At the same time, under a certain sintering system, more crystals are generated in the binder, thereby improving the sharpness and toughness of the abrasive tool.

[0033] As an example, the present invention provides a method for preparing a CBN grinding tool, comprising the following steps: firstly, mixing the CBN abrasive, the ceramic binder and the resin liquid in the formula, drying after cold pressing, and then sintering to prepare the CBN grinding tool. The mixing time is 10-45 minutes, preferably 25 minutes; the density of the CBN grinding tool obtained by molding is 2-3.5g / cm 3 , preferably 2.2 g / cm 3 ; The drying temperature is 120-160°C, the drying time is 5-12h, preferably 8h; the sintering temperature is 700-950°C, preferably 800°C; the sintering heating rate is 5-15°C / h, preferably 10°C / h; the sintering holding time is 1-3h, preferably 2h.

[0034] The present invention provides the use of the above-mentioned CBN grinding tool in machining the inner circle of a compressor; preferably, the inner circle of the compressor is the inner circle of an air-conditioning compressor. Embodiment 1

[0035] A preparation method of a ceramic binder comprises the following steps: dissolving 0.3 mol of yttrium nitrate, 0.5 mol of aluminum nitrate and 0.5 mol of zirconium nitrate in 500 ml of deionized water, and stirring the mixture magnetically at 65 DEG C for 1 hour; adding 0.3 mol of citric acid and stirring the mixture for 1 hour; adding ammonia water to adjust the pH value of the solution to 2.5, and then adding 75 g of ethyl orthosilicate and 130 g of boric acid and stirring the mixture for 1 hour, and then pouring the solution into a corundum crucible; placing the corundum crucible containing the solution in a muffle furnace, heating the temperature from room temperature to 400 DEG C at a heating rate of 40 DEG C / min, keeping the temperature for 2 hours, and then ball milling the obtained powder after natural cooling, wherein the weight ratio of the material, the ball and the alcohol is 1:1:0.4, the speed of the ball mill is 500 r / min, and the ball milling is performed for 4 hours; drying and sieving the ball-milled slurry, and taking powder with a particle size of 1-3 μm to obtain the ceramic binder.

[0036] Figure 1The following is a process map for preparing the ceramic binder of the present invention: Figure 2 This is the photo before ball milling.

[0037] Comparative Example 1 The difference from Example 1 is that the solution is heated from room temperature to 600°C at a heating rate of 40°C / min and kept warm for 2h. It is found that the product is a black solidified product with residual carbon wrapped in a glass phase and cannot be used as a ceramic binder. No subsequent ball milling is performed. Figure 3 This is a photo before ball milling, not suitable for binder. Embodiment 2

[0038] A CBN grinding tool comprises the following raw materials: 80 g of CBN abrasive, 15 g of the ceramic binder of Example 1 and 5 g of phenolic resin liquid.

[0039] The preparation method is as follows: (1) Mixing: stir and mix the CBN abrasive, ceramic binder and resin liquid evenly for 25 minutes; (2) Molding: cold press the mixture in step (1) into a mold with a molding density of 2.2 g / cm 3 , mold specifications: 1A8W 13.5×20×101×M20 CBN140 N200 grinding wheel linear speed 22 m / s; (3) Drying: drying the CBN abrasive tool formed in step (2) in an oven at a drying temperature of 150° C. for 8 h; (4) Sintering: The dried CBN abrasive tool in step (3) is placed in a muffle furnace for sintering at a heating rate of 10°C / h from room temperature to 800°C, kept at this temperature for 2h, and then naturally cooled to room temperature to obtain a CBN abrasive tool. The scanning electron micrograph is shown in FIG. Figure 4 . Embodiment 3

[0040] The difference from Example 1 is that 0.2 mol of yttrium nitrate, 0.7 mol of aluminum nitrate, 0.4 mol of zirconium nitrate, 90 g of tetraethyl orthosilicate, and 130 g of boric acid are used; the rest is the same. The ceramic binder is used to prepare a grinding tool with reference to Example 2. Embodiment 4

[0041] The difference from the second embodiment is that the sintering temperature of the grinding wheel is 750°C. Embodiment 5

[0042] The difference from Example 1 is that the amount of citric acid added is 1 mol; the rest is the same. The ceramic binder is used to prepare a grinding tool with reference to Example 2. Embodiment 6

[0043] The difference from Example 1 is that the temperature is raised from room temperature to 350° C. at a heating rate of 10° C. / min and kept at that temperature for 3 hours; the rest is the same. A grinding tool is prepared with this ceramic binder in accordance with Example 2.

[0044] Comparison Example A method for preparing an existing ceramic bond CBN grinding tool, wherein the bonding agent used in the grinding tool is oxide (yttrium oxide, zirconium oxide, aluminum oxide, silicon oxide and boric acid), which is prepared by smelting for 2 hours and water quenching and ball milling, which is equivalent to the raw materials and proportions of Example 1, and then the grinding tool is prepared with reference to Example 2.

[0045] Comparative Example 2 The difference from Example 1 is that boric acid is not added; the rest is the same. The abrasive tool is prepared with this ceramic binder in accordance with Example 2.

[0046] Comparative Example 3 The difference from Example 1 is that zirconium nitrate is not added; the rest is the same. A grinding tool is prepared with this ceramic binder in accordance with Example 2.

[0047] Test example According to the conventional method, the grinding tools of the embodiment and the comparative example were used as the inner circle grinding tools of the air-conditioning compressor respectively, and parallel experiments were carried out. The specific performance test results are shown in Table 1. The roughness and roundness are the results within the dressing interval.

[0048] Table 1 Abrasive tool performance test results of examples and comparative examples

[0049] It can be seen from the test results in Table 1 that the grinding wheel obtained in the embodiment has a good grinding life, a fast processing cycle, and a stable taper. For the preparation of traditional vitrified binders, the preparation of binders requires high-temperature smelting, thereby improving the performance of the binder, enhancing the wetting effect of the binder on the abrasive, and ultimately improving the performance of the abrasive tool. This is common knowledge in the art, but the smelting process of the binder preparation consumes a lot of energy and resources. The present invention prepares vitrified binders by a solution insulation method, omitting the smelting link, saving energy and resources, being easy to operate, and having slightly better performance than smelting binders.

[0050] In comparative example 2, boric acid was not added, resulting in the binder being unable to effectively wrap the abrasive at the sintering temperature, and the sintered grinding wheel had no strength and could not be used normally. In comparative example 3, zirconium nitrate was not added, and the grinding effect of the prepared abrasive tool was poor, and the dressing interval was significantly reduced.

[0051] As a silicate glass material, the ceramic binder of superhard abrasive tools can obtain high-strength performance through melting, but its sharpness is weak, which is limited for some processing scenarios with high sharpness requirements. The present invention prepares the ceramic binder through the solution insulation method, which improves its sharpness through crystallization while ensuring the strength of the binder. The solution insulation method significantly reduces production costs and production energy consumption, and has better use value; and the prepared grinding wheel has better processing effect than existing products.

[0052] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A method for preparing a ceramic binder by heat preservation of a solution, comprising the following steps: The liquid containing metal nitrate, water-soluble additive, tetraethyl orthosilicate and boric acid is heat-treated to obtain a powder; The powder is then ground to obtain a ceramic binder.

2. A method for preparing a superhard abrasive tool, comprising the following steps: heat-treating a liquid containing metal nitrate, a water-soluble additive, tetraethyl orthosilicate and boric acid to obtain a powder; grinding the powder to obtain a ceramic binder; and mixing the abrasive, the ceramic binder and the resin liquid, forming, drying and sintering the mixture to obtain a superhard abrasive tool.

3. The preparation method according to claim 1 or 2, characterized in that: The metal nitrate includes one or more of yttrium nitrate, aluminum nitrate, zirconium nitrate and zinc nitrate; the water-soluble additive includes one or more of citric acid, sucrose, urea and polyethylene glycol.

4. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of the water-soluble additive to the total metal ions in the metal nitrate is (0.1-3.5):1; by weight, the amount of ethyl orthosilicate added is 15-30% of the metal nitrate, and the amount of boric acid added is 30-50% of the metal nitrate.

5. The preparation method according to claim 1 or 2, characterized in that: The pH of the system containing metal nitrate and water-soluble additive is maintained at 2-4, and then ethyl orthosilicate and boric acid are added to obtain a liquid; the heat preservation treatment is carried out in an oxygen-containing gas at 250-500° C. for 0.5-8 hours.

6. The preparation method according to claim 2, characterized in that: The weight ratio of abrasive, ceramic binder and resin liquid is (65-85): (5-25): (3-5).

7. A vitrified binder or superhard abrasive tool prepared according to the preparation method of claim 1 or 2.

8. Use of the ceramic binder according to claim 7 in the preparation of superhard abrasive tools.

9. Application of the superhard abrasive tool as claimed in claim 7 in the internal machining of compressors.

10. A method for machining the inner circle of a compressor, comprising the following steps: machining the inner circle of the compressor using the superhard abrasive tool as claimed in claim 7 to complete the machining of the inner circle of the compressor.

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