Glass ceramic processing and surface treatment process

Abstract

The invention discloses a glass ceramic processing and surface treatment process. Comprising the following steps of wire cutting, acid pickling after cutting, CNC forming, polishing and thinning, upper sweeping and lower polishing, edge polishing, first ultrasonic cleaning, acid pickling before first-stage strengthening, second ultrasonic cleaning, first-stage strengthening, third ultrasonic cleaning, second-stage strengthening, fourth ultrasonic cleaning, acid pickling after second-stage strengthening and fifth ultrasonic cleaning. The glass ceramic surface processing and treatment process provided by the invention can effectively improve the surface roughness of the glass, has a very good effect on repairing the surface microcracks of the polished and strengthened glass, and can effectively improve the body strength of the glass ceramic, including the four-point flexural strength, the falling ball strength, the edge pressing performance and the like of the glass ceramic.

Description

Technical Field

[0001] This invention relates to the field of microcrystalline glass processing technology, and in particular to a microcrystalline glass processing and surface treatment process. Background Technology

[0002] Currently, microcrystalline glass mobile phone protective films and cover plates are generally manufactured using CNC precision engraving machines, typically including the following processes: wire cutting, CNC shaping, grinding, polishing, peripheral polishing, 2D curved surface sweeping, strengthening, cleaning, and packaging. Traditional processes to increase the strength of the glass body include surface polishing and primary strengthening. However, surface mechanical polishing can cause microcracks in the microcrystalline glass, resulting in the glass body's strength failing to meet requirements. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a microcrystalline glass processing and surface treatment process that can effectively improve the bulk strength of microcrystalline glass.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A microcrystalline glass processing and surface treatment process includes the following steps:

[0006] First-stage pre-strengthening pickling: The polished glass is immersed in a pre-strengthening acid solution, which is a mixture of hydrofluoric acid, hydrochloric acid, sulfuric acid and nitric acid;

[0007] Primary strengthening: Glass that has undergone pickling before primary strengthening is subjected to primary strengthening using a high-temperature molten mixture of potassium nitrate and sodium nitrate.

[0008] Secondary strengthening: Glass that has undergone primary strengthening is subjected to secondary strengthening using a high-temperature molten mixture of potassium nitrate and lithium nitrate.

[0009] Pickling after secondary strengthening: The glass that has undergone secondary strengthening is immersed in a strengthening acid solution, which is a mixture of hydrofluoric acid, hydrochloric acid, sulfuric acid and nitric acid.

[0010] In a preferred embodiment of the present invention, the pre-strengthening pickling step is carried out in an environment with a room temperature of 19℃~26℃ and a humidity of 40%~60%. The pre-strengthening acid solution is prepared with hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, and pure water, wherein the volume percentage of hydrofluoric acid is ≥2.56%, the volume percentage of nitric acid is ≥1.1%, and the combined volume percentage of hydrochloric acid and sulfuric acid is ≥0.21%. More preferably, the volume ratio of hydrofluoric acid: hydrochloric acid: sulfuric acid: nitric acid: pure water is 2000:50:100:1000:81000. The pre-strengthening pickling step mainly removes microcracks at a depth of 1~3μm on the glass surface after polishing, repairs residual stress from the glass brushing and grinding processes and the edge polishing process, removes surface cracks, and improves the roughness of all flat and curved surfaces of the glass; the glass removal rate is ≥0.018~0.025mm / min, and the removal amount is 0.018~0.025mm.

[0011] In the pre-strengthening pickling step, residual stress after the upper and lower grinding processes and edge polishing of the microcrystalline glass can be repaired, surface cracks in the microcrystalline glass can be removed, and the roughness of all flat and curved surfaces of the microcrystalline glass can be improved. The pre-strengthening acid solution is prepared with hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, and pure water. All four acids are analytical grade. Among them, hydrofluoric acid mainly plays a role in chemical thinning, hydrochloric acid plays a role in relieving glass stress, and sulfuric acid and nitric acid mainly play a role in reducing the surface tension of the glass and preventing dust and dirt from adhering to the new surface of the thinned glass.

[0012] In a preferred embodiment of the present invention, in the primary strengthening step, the microcrystalline glass is inserted facetwise onto a stainless steel frame (wound with metal or a metal part) and immersed in a high-temperature molten potassium nitrate and sodium nitrate mixture, with a mass ratio of potassium nitrate / (potassium nitrate and sodium nitrate mixture) of 50-90%; the strengthening time is 120-360 minutes, preferably 180-360 minutes; and the strengthening temperature is 350-500°C, preferably 380-420°C. This method slowly increases the stress layer on the glass surface and forms compressive stress, preventing the stress layer depth and stress increase from being too rapid, which could damage the glass surface finish, amplify microcracks on the glass surface, and reduce the glass strength.

[0013] As a preferred embodiment of the present invention, in the first-stage strengthening step, the purity of potassium nitrate is 99.5% to 99.999%, and the purity of sodium nitrate is 99.5% to 99.999%.

[0014] As a preferred embodiment of the present invention, in the secondary strengthening step, the microcrystalline glass is inserted facet by facet onto a stainless steel frame (wound metal or metal part), and immersed in a high-temperature molten potassium nitrate and lithium nitrate mixture, wherein the mass ratio of potassium nitrate / (potassium nitrate and lithium nitrate mixture) is 85-99%; the strengthening time is 15-180 minutes, and the strengthening temperature is 350-500°C, more preferably 380-420°C.

[0015] Primary and secondary strengthening employ two different high-temperature molten liquids to generate two ion replacement reactions on the glass surface and form two stress layers.

[0016] In a preferred embodiment of the present invention, in the secondary strengthening step, the purity of potassium nitrate is 99.5% to 99.999%, and the purity of lithium nitrate is 99.5% to 99.999%.

[0017] In a preferred embodiment of the present invention, the pickling step after secondary strengthening is carried out at room temperature of 19°C to 26°C and humidity of 40% to 60%. The strengthened acid solution is prepared with hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid and pure water, wherein the volume percentage of hydrofluoric acid is ≥2.56%, the volume percentage of nitric acid is ≥1.1%, and the combined volume percentage of hydrochloric acid and sulfuric acid is ≥0.21%. More preferably, the volume ratio of hydrofluoric acid: hydrochloric acid: sulfuric acid: nitric acid: pure water is 2000:30:150:1000:85000. The secondary strengthening pickling step mainly removes microcracks at a depth of 2µm on the glass surface after polishing, repairs residual stress from the glass sweeping and grinding process and the edge polishing process, removes cracks on the glass surface, and improves the roughness of all flat and curved surfaces of the glass. The roughness after removal can reach 0.01µm. The glass removal rate is ≥0.018~0.025mm / min, and the removal amount is 0.018~0.025mm.

[0018] In the secondary strengthening pickling step, the strengthening acid solution is prepared with hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid and pure water. All four acids are analytical grade. The acid solution repairs residual stress from high-temperature strengthening of the glass and removes cracks on the glass surface, thereby improving the roughness of all flat and curved surfaces of the glass.

[0019] As a preferred embodiment of the present invention, the microcrystalline glass processing and surface treatment process includes the following steps: wire cutting, pickling after cutting, CNC forming, polishing and thinning, top sweeping and bottom polishing, edge polishing, first ultrasonic cleaning, pickling before the first-stage strengthening, second ultrasonic cleaning, first-stage strengthening, third ultrasonic cleaning, second-stage strengthening, fourth ultrasonic cleaning, pickling after the second-stage strengthening, and fifth ultrasonic cleaning.

[0020] As a preferred embodiment of the present invention, the microcrystalline glass processing and surface treatment process includes the following steps:

[0021] Wire cutting: The pre-shaped microcrystalline glass brick material is wire cut to the designed thickness to form sheets;

[0022] Pickling after cutting: The cut sheet-shaped microcrystalline glass is immersed in hydrochloric acid solution to eliminate cutting stress;

[0023] CNC forming: The microcrystalline glass after the cutting stress is eliminated is processed into the required shape, as well as 2.5D, 2D or C-corner;

[0024] Polishing and thinning: The CNC-formed microcrystalline glass is polished and thinned to the required thickness, while improving cracks on the glass surface.

[0025] Upward sweeping and downward polishing: sweeping the R-curve surface of the microcrystalline glass after the polishing and thinning treatment, and reducing the planar thickness of the microcrystalline glass;

[0026] Edge polishing: The microcrystalline glass is divided into layers and stacked, and the edges of the microcrystalline glass and the upper and lower edges are polished by an edge polishing machine.

[0027] First ultrasonic cleaning: Ultrasonic cleaning is performed on the microcrystalline glass that has been edge-polished.

[0028] First-stage pre-strengthening pickling: The microcrystalline glass, after polishing and ultrasonic cleaning, is immersed in a pre-strengthening acid solution, which is a mixture of hydrofluoric acid, hydrochloric acid, sulfuric acid and nitric acid.

[0029] Second ultrasonic cleaning: Ultrasonic cleaning is performed on the microcrystalline glass that has undergone acid pickling before primary strengthening.

[0030] Primary strengthening: The microcrystalline glass, after being acid-washed and ultrasonically cleaned before primary strengthening, is subjected to primary strengthening using a high-temperature molten potassium nitrate and sodium nitrate mixture.

[0031] Third ultrasonic cleaning: Ultrasonic cleaning is performed on the microcrystalline glass that has undergone primary strengthening.

[0032] Secondary strengthening: The microcrystalline glass that has undergone primary strengthening and ultrasonic cleaning is subjected to secondary strengthening using a high-temperature molten potassium nitrate and lithium nitrate mixture;

[0033] Fourth, ultrasonic cleaning: Ultrasonic cleaning is performed on the microcrystalline glass that has undergone secondary strengthening.

[0034] Secondary strengthening followed by pickling: The microcrystalline glass that has undergone secondary strengthening and ultrasonic cleaning is immersed in a strengthening acid solution, which is a mixture of hydrofluoric acid, hydrochloric acid, sulfuric acid and nitric acid.

[0035] Fifth, ultrasonic cleaning: The microcrystalline glass that has undergone secondary strengthening and acid washing is then subjected to ultrasonic cleaning.

[0036] As a preferred embodiment of the present invention, in the wire cutting step, a combination of 7um or 12um diamond wire and silicon carbide cutting fluid is used for wire cutting to obtain better surface quality.

[0037] As a preferred embodiment of the present invention, in the acid washing step after cutting, the cut sheet-like microcrystalline glass is inserted into an acid-resistant rack, preferably at a room temperature of 22℃-26℃; the hydrochloric acid solution has a hydrochloric acid volume content of 3-20%, preferably 3%-15%, and the soaking time is 3-15 minutes, and the hydrochloric acid is analytical grade pure hydrochloric acid.

[0038] As a preferred embodiment of the present invention, in the CNC forming step, a CNC machining equipment is used. First, a corner fixture is designed, and then the glass is machined into the required shape by a grinding head and an NC program. The grinding head is mostly made of electroplated diamond and sintered. A suitable grinding head and NC program are selected for machining. Specifically, when rough machining the glass shape and chamfering, an electroplated diamond grit of 300# to 400# is selected, and when finishing the glass shape and chamfering, an electroplated diamond grit of 1000# to 1500# is selected. The concentricity of the grinding head is 0 to 0.01 mm. The feed rate of the NC program is 500 to 1000 mm / min, and the feed amount is 0.01 to 0.05 mm / time, which further reduces and minimizes breakage, chipped corners, and microcracks caused by glass processing stress.

[0039] In a preferred embodiment of the present invention, in the polishing and thinning step, a double-sided flat polishing machine is used. The upper and lower discs are covered with polyurethane polishing skin or non-woven fabric polishing skin with a hardness of 70-83. The thickness of the polishing skin is 2.5-4.0 mm. A planetary wheel with a composite design of epoxy resin and steel plate is selected. The planetary wheel cavity is 0.05-0.25 mm larger than the microcrystalline glass on one side, and the planetary wheel thickness is 0.03-0.08 μm smaller than the microcrystalline glass. Cerium oxide polishing powder or aluminum oxide polishing powder is used, with a particle size of 1.2-1.5 μm and a powder solution density of 1.10-1.16 g / cm³. The original frosted surface of the microcrystalline glass is polished to a mirror finish, and the surface is simultaneously thinned to the designed required thickness during the polishing process.

[0040] As a preferred embodiment of the present invention, in the polishing and thinning step, the hardness of the polyurethane polishing skin or non-woven polishing skin is 73-82; the thickness of the planetary wheel is 0.03-0.05 mm smaller than that of the microcrystalline glass; and the density of the polishing powder is 1.12-1.14 g / cm³.

[0041] As a preferred embodiment of the present invention, in the above-sweeping and below-polishing step, the polished and thinned 2.5D / 2D microcrystalline glass is divided into facets, with the R-face of the 2.5D effect facing upwards and the C-corner facing downwards, and placed inside an epoxy board cavity with a hybrid structure design that is 0.05-0.3mm larger on each side than the microcrystalline glass. The R-curved surface of the microcrystalline glass is polished using an above-sweeping and below-grinding method with a double-sided flat polishing machine (20B, 16B, 15B, 13B). A carpet with a pile length of 5-25mm is attached to the upper plate, and a polishing leather with a hardness of 70-83 is attached to the lower plate. The polishing leather is a polyurethane polishing leather or a non-woven fabric polishing leather with a thickness of 2.5-4.0mm. Cerium oxide polishing powder or aluminum oxide polishing powder is used, with a particle size of 1.0-1.5um and a solution density of 1.10-1.16g / cm³.

[0042] As a preferred embodiment of the present invention, in the above sweeping and below polishing steps, the upper plate is fitted with a carpet with a pile length of 10-25mm, and the polishing powder has a particle size of 1.0-1.2um.

[0043] In a preferred embodiment of the present invention, in the edge polishing step, a brush wheel with a bristle length of 15-30 mm is selected, the bristles are made of soft pig bristles and / or horsehair, and the polishing powder is cerium oxide or aluminum oxide with a particle size of 1.0-1.2 μm, removing 0.005-0.02 mm of material from the glass surface. Edge polishing can repair and improve surface cracks at glass chamfers and corners.

[0044] In a preferred embodiment of the present invention, in the first ultrasonic cleaning step, the microcrystalline glass, after edge polishing, is inserted into a PP material cleaning rack and then placed in an oxalic acid solution bath or a citric acid solution bath at 30-35°C for ultrasonic cleaning. The mass concentration of the oxalic acid solution is ≤30%, and the mass concentration of the citric acid solution is ≤30%. This cleans the glass surface of the exposure powder / polishing liquid and other impurities. More preferably, a cleaning agent with an oxalic acid to pure water mass ratio of 15:100 is used, which can better remove residual cerium oxide or aluminum oxide solution.

[0045] As a preferred embodiment of the present invention, in the second ultrasonic cleaning step, the microcrystalline glass is inserted facet to the PP material cleaning rack, and the residual mixed acid and other impurities on the surface of the microcrystalline glass are cleaned by ultrasonic cleaning. A cleaning agent with a pH value of 8 to 10 is selected for ultrasonic cleaning.

[0046] As a preferred embodiment of the present invention, in the third ultrasonic cleaning step, the microcrystalline glass is inserted facet to the PP material cleaning rack, and the residual potassium nitrate and sodium nitrate, as well as other impurities on the surface of the microcrystalline glass are cleaned by ultrasonic cleaning; a cleaning agent with a pH value of 8 to 10 is selected for ultrasonic cleaning.

[0047] As a preferred embodiment of the present invention, in the fourth ultrasonic cleaning step, the microcrystalline glass is inserted facet to the PP material cleaning rack, and the residual potassium nitrate and lithium nitrate, as well as other impurities on the surface of the microcrystalline glass are cleaned by ultrasonic cleaning; a cleaning agent with a pH value of 8 to 10 is selected for ultrasonic cleaning.

[0048] As a preferred embodiment of the present invention, in the fifth ultrasonic cleaning step, the microcrystalline glass is inserted facet to the PP material cleaning rack, and the residual mixed acid and other impurities on the surface of the microcrystalline glass are cleaned by ultrasonic cleaning. A cleaning agent with a pH value of 8 to 10 is selected for ultrasonic cleaning.

[0049] As a preferred embodiment of the present invention, the surface processing and treatment technology of the microcrystalline glass is particularly suitable for microcrystalline glass with low lithium content, and can effectively improve the bulk strength of microcrystalline glass with low lithium content.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0051] (1) The microcrystalline glass surface processing and treatment technology provided by this invention has two key aspects: 1. It adopts a primary strengthening process and a secondary strengthening process; 2. It performs an acid pickling process before the primary strengthening process and after the secondary strengthening process. These two chemical acid pickling processes can effectively improve the surface roughness of the glass, and have a very good effect on repairing surface microcracks after glass polishing and strengthening. It can effectively improve the body strength of the microcrystalline glass, including improving the four-point flexural strength, drop ball strength and edge pressing performance of the microcrystalline glass. Detailed Implementation

[0052] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Unless otherwise specified, the raw materials, equipment, etc., used in the following embodiments can all be obtained through commercial channels.

[0053] Example 1

[0054] A microcrystalline glass processing and surface treatment process includes the following steps:

[0055] (1) Wire cutting: The pre-shaped microcrystalline glass brick material with length and width dimensions is cut into sheets of the required thickness. The wire cutting thickness is controlled by the designed roller spacing. Wire cutting is performed using a combination of 7um diamond wire and silicon carbide cutting fluid.

[0056] (2) Pickling after cutting: Insert the microcrystalline glass after wire cutting into the PP material frame and immerse it in a hydrochloric acid solution with an analytical grade hydrochloric acid content of 10% (diluted with pure water) for 10 minutes at a room temperature of 25°C to eliminate residual stress caused by the extrusion during the wire cutting process and prevent the glass from breaking.

[0057] (3) CNC forming: CNC machining equipment is used. First, the corner fixture is designed. The grinding head and NC program are used to process the full circumference cross section (2.5D arc surface / C angle) required by the design. The grinding head adopts electroplated diamond and sintering method. The electroplated diamond grit is 300# and the concentricity of the grinding head is 0.01mm. The feed rate of the NC program is 800mm / min and the feed amount is 0.03mm / time, which further reduces and minimizes the damage, missing corners and microcracks caused by glass processing stress.

[0058] (4) Polishing and thinning: A double-sided flat polishing machine is used, with polyurethane polishing pads (2.5-4.0mm thick) of hardness 73-82 applied to the upper and lower discs. A planetary wheel is designed using a composite of epoxy resin and steel plate. The planetary wheel cavity is 0.2mm larger than the glass on one side, and the planetary wheel thickness is 0.05μm smaller than the glass. The average particle size of the polishing powder is 1.3μm, and the density of the cerium oxide polishing solution is 1.12g / cm³. The original frosted surface of the microcrystalline glass is polished into a mirror finish, and the surface is simultaneously thinned to the designed thickness during the polishing process.

[0059] (5) Top sweeping and bottom polishing: Use a double-sided flat polishing machine (15B), with carpet (pile length 10-25mm) on the upper plate and polishing leather (70-83 hardness polyurethane polishing leather, thickness 2.8mm) on the lower plate. The average particle size of the polishing powder is 1.0um, and the density of the cerium oxide polishing liquid solution is 1.12 g / cm³. Polish the 2.5D curved surface and reduce the thickness of the flat surface to the designed thickness and brightness effect.

[0060] (6) Edge Polishing: Stack the 2.5D effect glass from step (5) with the R-side facing up and the C-corner facing down, place them in an edge polishing fixture and secure them. Use a brush wheel with a bristle length of 15-20mm to polish the 2.5D curved surface, C-corner, and other surfaces of the glass. The bristle material is soft horsehair, and the polishing powder is cerium oxide with a particle size of 1.0-1.2um. The amount of glass surface removed is 0.005-0.01mm. Edge polishing can repair and improve surface cracks on glass chamfers and corners.

[0061] (7) First ultrasonic cleaning: Insert the microcrystalline glass that has been edge-polished into the PP material cleaning rack, finely polish it in an oxalic acid solution bath at 32°C (the mass concentration of the oxalic acid solution is 30%), and use an ultrasonic cleaning machine to clean the glass surface of residual polishing powder / polishing liquid and other foreign matter.

[0062] (8) Pre-strengthening pickling: Under conditions of room temperature 22℃ and humidity 40%~60%, the cleaned microcrystalline glass is immersed in the pre-strengthening acid solution. The pre-strengthening acid solution is prepared with hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid and pure water, with a volume ratio of hydrofluoric acid: hydrochloric acid: sulfuric acid: nitric acid: pure water = 2000:50:100:1000:81000; the glass removal rate is ≥0.018~0.025mm / min, and the removal amount is 0.018~0.025mm. This improves the roughness of all flat and curved surfaces of the glass, eliminates residual stress from the glass sweeping and grinding process and edge polishing, and repairs and removes microcracks on the glass surface.

[0063] (9) Second ultrasonic cleaning: Use a weak alkaline cleaning agent with a pH of 8 to more effectively remove residual acid and other foreign matter from the surface of the microcrystalline glass.

[0064] (10) Primary strengthening: The microcrystalline glass is inserted facet by facet onto a stainless steel frame wrapped with metal, and immersed in a high-temperature molten potassium nitrate and sodium nitrate mixture. The mass ratio of potassium nitrate to (potassium nitrate and sodium nitrate mixture) is 75%. The strengthening time is 200 minutes, and the strengthening temperature is 400℃. The purity of potassium nitrate is 99.5%, and the purity of sodium nitrate is 99.5%.

[0065] (11) Third ultrasonic cleaning: Insert the glass surface after step (10) into the PP material cleaning rack, select a weak alkaline cleaning agent with a pH value of 8, and use ultrasonic cleaning to clean the residual potassium nitrate and sodium nitrate, as well as other impurities on the glass surface.

[0066] (12) Secondary strengthening: The microcrystalline glass is inserted facet by facet onto a stainless steel frame wrapped with metal, and immersed in a high-temperature molten potassium nitrate and lithium nitrate mixture. The mass ratio of potassium nitrate / (potassium nitrate and lithium nitrate mixture) is 90%; the strengthening time is 30 minutes and the strengthening temperature is 380℃; the purity of potassium nitrate is 99.5% and the purity of lithium nitrate is 99.5%.

[0067] (13) Fourth ultrasonic cleaning: Use a weak alkaline cleaning agent with a pH of 8 to more effectively remove residual potassium nitrate and lithium nitrate, as well as other foreign matter, from the surface of the microcrystalline glass.

[0068] (14) Secondary strengthening followed by pickling: In an environment with room temperature of 23℃ and humidity of 40%–60%, the cleaned glass is immersed in the strengthened acid solution. The strengthened acid solution is prepared with hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, and pure water. The volume ratio of hydrofluoric acid: hydrochloric acid: sulfuric acid: nitric acid: pure water is 2000:30:150:1000:85000. The glass removal rate is ≥0.018–0.025 mm / min, and the removal amount is 0.018–0.025 mm. This process repairs the residual stress from the upper and lower grinding steps and edge polishing of the glass, removes micro-cracks on the glass surface, and improves the roughness of all flat and curved surfaces of the glass.

[0069] (15) Fifth ultrasonic cleaning: Use a weak alkaline cleaning agent with a pH of 8 to more effectively remove residual acid and other foreign matter from the surface of the microcrystalline glass.

[0070] Example 2

[0071] The difference between Example 2 and Example 1 is that:

[0072] (1) Wire EDM: Wire EDM is performed using a combination of 12µm diamond wire and silicon carbide cutting fluid.

[0073] (2) Pickling after cutting: Soak in a 20% (diluted with pure water) hydrochloric acid solution of analytical grade for 12 minutes at a room temperature of 23°C.

[0074] (3) CNC forming: the electroplated diamond grit is 1000#, the concentricity of the grinding head is 0.005mm; the feed rate of the NC program is 1000mm / min, and the feed amount is 0.05mm / time.

[0075] (4) Polishing and thinning: The planetary wheel cavity is 0.2 mm larger than the glass on one side, the planetary wheel thickness is 0.08 μm smaller than the glass, the average particle size of the polishing powder is 1.3 μm, and the density of the cerium oxide polishing liquid solution is 1.12 g / cm³.

[0076] (5) Top sweep and bottom polishing: The average particle size of the polishing powder is 1.5 μm, and the density of the cerium oxide polishing solution is 1.16 g / cm³.

[0077] (6) Edge polishing: Select a brush wheel with a bristle length of 20-30mm, the bristle material is soft pig bristles, and the polishing powder is aluminum oxide with a particle size of 1.0-1.2um. The amount of glass surface removed is 0.01-0.02mm.

[0078] (7) First ultrasonic cleaning: In an oxalic acid solution bath at 35°C, the mass concentration of the oxalic acid solution is 25%.

[0079] (8) First-level pickling before strengthening: by volume ratio, hydrofluoric acid: hydrochloric acid: sulfuric acid: nitric acid: pure water = 2300: 60: 120: 1200: 80000.

[0080] (9) Second ultrasonic cleaning: Use a weak alkaline cleaning agent with a pH value of 10.

[0081] (10) Primary strengthening: by mass ratio, potassium nitrate / (mixture of potassium nitrate and sodium nitrate) = 50%; strengthening time is 360 minutes, strengthening temperature is 350℃, the purity of potassium nitrate is 99.999%, and the purity of sodium nitrate is 99.999%.

[0082] (11) Third ultrasonic cleaning: Use a weak alkaline cleaning agent with a pH value of 10.

[0083] (12) Secondary reinforcement: by mass ratio, potassium nitrate / (potassium nitrate and lithium nitrate mixture) = 85%; reinforcement time is 50 minutes, reinforcement temperature is 500℃; the purity of potassium nitrate is 99.999%, and the purity of lithium nitrate is 99.999%.

[0084] (13) Fourth ultrasonic cleaning: Select a weak alkaline cleaning agent with a pH value of 10.

[0085] (14) Pickling after secondary reinforcement: by volume ratio, hydrofluoric acid: hydrochloric acid: sulfuric acid: nitric acid: pure water = 2500: 50: 170: 1500: 86000.

[0086] (15) Fifth ultrasonic cleaning: Use a weak alkaline cleaning agent with a pH value of 10.

[0087] Comparative Example 1

[0088] The difference between Comparative Example 1 and Example 1 is that the following four steps are omitted: (8) pre-enhancing pickling step, (9) second ultrasonic cleaning step, (14) post-enhancing pickling step, and (15) fifth ultrasonic cleaning step. The rest is the same as in Example 1.

[0089] Comparative Example 2

[0090] The difference between Comparative Example 2 and Example 1 is that the (8) first-stage pre-enhancing acid washing and (9) second ultrasonic cleaning steps are omitted, while the rest are the same as in Example 1.

[0091] Comparative Example 3

[0092] The difference between Comparative Example 3 and Example 1 is that the (14) secondary strengthening pickling and (15) fifth ultrasonic cleaning steps are omitted, while the rest are the same as Example 1.

[0093] Comparative Example 4

[0094] The difference between Comparative Example 4 and Example 1 is that: (12) in the secondary strengthening step, a high-temperature molten potassium nitrate and sodium nitrate mixture is used, just as in (10) the primary strengthening step. The rest is the same as in Example 1.

[0095] Comparative Example 5

[0096] The difference between Comparative Example 5 and Example 1 is that:

[0097] The composition of the acid solution before and after enhancement was changed, and hydrochloric acid was omitted in both cases;

[0098] (8) First-stage pickling before strengthening: The acid solution before strengthening is prepared with hydrofluoric acid, sulfuric acid, nitric acid and pure water. The volume ratio is hydrofluoric acid: sulfuric acid: nitric acid: pure water = 2000: 100: 1000: 81000.

[0099] (14) Pickling after secondary reinforcement: The acid solution after reinforcement is prepared with hydrofluoric acid, sulfuric acid, nitric acid and pure water. The volume ratio is hydrofluoric acid: sulfuric acid: nitric acid: pure water = 2000: 150: 1000: 85000.

[0100] The rest is the same as in Example 1.

[0101] Comparative Example 6

[0102] The difference between Comparative Example 6 and Example 1 is that:

[0103] The composition of the acid solution before and after enhancement was changed, and sulfuric acid was omitted in both cases;

[0104] (8) First-stage pickling before strengthening: The acid solution before strengthening is prepared with hydrofluoric acid, hydrochloric acid, nitric acid and pure water. The volume ratio is hydrofluoric acid: hydrochloric acid: nitric acid: pure water = 2000: 50: 1000: 81000.

[0105] (14) Pickling after secondary strengthening: The acid solution after strengthening is prepared with hydrofluoric acid, hydrochloric acid, nitric acid and pure water. The volume ratio is hydrofluoric acid: hydrochloric acid: nitric acid: pure water = 2000: 30: 1000: 85000.

[0106] The rest is the same as in Example 1.

[0107] Performance testing

[0108] The microcrystalline glass obtained after processing in Examples 1-2 and Comparative Examples 1-5 were subjected to performance tests. The test indicators and methods are as follows:

[0109] Table 1 Performance Test Results Record Table

[0110] Four-point flexural strength (MPA) Drop ball test intensity (meters) Edge compressive strength (MPa) Example 1 682 1.5 615 Example 2 673 1.5 610 Comparative Example 1 628 1.0 554 Comparative Example 2 630 1.1 563 Comparative Example 3 635 1.1 565 Comparative Example 4 645 1.1 583 Comparative Example 5 650 1.2 586 Comparative Example 6 648 1.1 590

[0111] Note: The drop ball strength test results in the table above are based on a 300g steel ball / solid ball test.

[0112] As can be seen from the records in Table 1, the microcrystalline glass of Examples 1-2 has a better bulk strength than the microcrystalline glass of Comparative Examples 1-6.

[0113] The microcrystalline glass surface processing and treatment technology provided in this invention uses small-particle diamond wire and abrasive for wire cutting. Simultaneously, appropriate materials are selected for double-sided polishing, sweeping, edge polishing, and cleaning processes. Crucially, the glass strengthening process is optimized, and chemical acid washing and polishing are performed both before and after strengthening to improve and repair microcracks (roughness) on the glass surface, eliminate mechanical processing stress, and enhance ion exchange stress to improve the strength of the microcrystalline glass body, thereby increasing the resin drop ball strength and edge crush strength of the microcrystalline glass. Compared with traditional brush polishing and mechanical repair processes, the process provided in this invention not only has better polishing effects but is also simpler, lower in cost, and easier to implement.

[0114] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A microcrystalline glass processing and surface treatment process, characterized in that, Includes the following steps: First-stage pre-strengthening pickling: The polished glass is immersed in a pre-strengthening acid solution, which is a mixture of hydrofluoric acid, hydrochloric acid, sulfuric acid and nitric acid; Primary strengthening: Glass that has undergone pickling before primary strengthening is subjected to primary strengthening using a high-temperature molten mixture of potassium nitrate and sodium nitrate. Secondary strengthening: Glass that has undergone primary strengthening is subjected to secondary strengthening using a high-temperature molten mixture of potassium nitrate and lithium nitrate. Pickling after secondary strengthening: The glass that has undergone secondary strengthening is immersed in a strengthening acid solution, which is a mixture of hydrofluoric acid, hydrochloric acid, sulfuric acid and nitric acid.

2. The microcrystalline glass processing and surface treatment process as described in claim 1, characterized in that, In the first-stage pre-strengthening pickling step, the pre-strengthening acid solution is prepared with hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, and pure water, wherein the volume percentage of hydrofluoric acid is ≥2.56%, the volume percentage of nitric acid is ≥1.1%, and the combined volume percentage of hydrochloric acid and sulfuric acid is ≥0.21%; it removes microcracks at a depth of 1-3 μm on the polished glass surface, with a glass removal rate ≥0.018-0.025 mm / min and a removal amount of 0.018-0.025 mm; In the first-stage strengthening step, the mass ratio of potassium nitrate to (a mixture of potassium nitrate and sodium nitrate) is 50-90%; the strengthening time is 180-360 minutes; and the strengthening temperature is 380-500°C. In the secondary strengthening step, the mass ratio of potassium nitrate / (mixture of potassium nitrate and lithium nitrate) is 85-99%; the strengthening time is 15-180 minutes; and the strengthening temperature is 380-500℃. In the secondary strengthening pickling step, the strengthened acid solution is prepared with hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid and pure water, wherein the volume percentage of hydrofluoric acid is ≥2.56%, the volume percentage of nitric acid is ≥1.1%, and the combined volume percentage of hydrochloric acid and sulfuric acid is ≥0.21%; microcracks at a depth of 2 μm are removed from the polished glass surface, the glass removal rate is ≥0.018~0.025 mm / min, and the removal amount is 0.018~0.025 mm.

3. The microcrystalline glass processing and surface treatment process as described in claim 2, characterized in that, In the first-stage pre-enhancing pickling step, the volume ratio of hydrofluoric acid: hydrochloric acid: sulfuric acid: nitric acid: pure water is 2000:50:100:1000:81000. In the aforementioned primary enhancement step, the purity of potassium nitrate is 99.5%–99.999%, and the purity of sodium nitrate is 99.5%–99.999%. In the secondary enhancement step, the purity of potassium nitrate is 99.5% to 99.999%, and the purity of lithium nitrate is 99.5% to 99.999%. In the secondary strengthening pickling step, the volume ratio of hydrofluoric acid: hydrochloric acid: sulfuric acid: nitric acid: pure water is 2000:30:150:1000:85000.

4. The microcrystalline glass processing and surface treatment process as described in claim 1, characterized in that, Includes the following steps: Wire cutting, pickling after cutting, CNC forming, polishing and thinning, top sweeping and bottom polishing, edge polishing, first ultrasonic cleaning, pickling before the first-stage strengthening, second ultrasonic cleaning, first-stage strengthening, third ultrasonic cleaning, second-stage strengthening, fourth ultrasonic cleaning, pickling after the second-stage strengthening, and fifth ultrasonic cleaning.

5. The microcrystalline glass processing and surface treatment process as described in claim 1, characterized in that, Includes the following steps: Wire cutting: Cutting microcrystalline glass bricks into sheets using wire cutting. Pickling after cutting: The cut sheet-shaped microcrystalline glass is immersed in hydrochloric acid solution to eliminate cutting stress; CNC forming: The microcrystalline glass after the cutting stress is eliminated is processed into the required shape, as well as 2.5D, 2D or C-corner; Polishing and thinning: Polishing and thinning the CNC-machined microcrystalline glass; Upward sweeping and downward polishing: sweeping the R-curve surface of the microcrystalline glass after the polishing and thinning treatment, and reducing the planar thickness of the microcrystalline glass; Edge polishing: The edge polishing machine is used to clean the chamfered edges of the microcrystalline glass, including the upper and lower surfaces. First ultrasonic cleaning: Ultrasonic cleaning is performed on the microcrystalline glass that has been edge-polished. First-stage pre-strengthening pickling: The microcrystalline glass, after polishing and ultrasonic cleaning, is immersed in a pre-strengthening acid solution, which is a mixture of hydrofluoric acid, hydrochloric acid, sulfuric acid and nitric acid. Second ultrasonic cleaning: Ultrasonic cleaning is performed on the microcrystalline glass that has undergone acid pickling before primary strengthening. Primary strengthening: The microcrystalline glass, after being acid-washed and ultrasonically cleaned before primary strengthening, is subjected to primary strengthening using a high-temperature molten potassium nitrate and sodium nitrate mixture. Third ultrasonic cleaning: Ultrasonic cleaning is performed on the microcrystalline glass that has undergone primary strengthening. Secondary strengthening: The microcrystalline glass that has undergone primary strengthening and ultrasonic cleaning is subjected to secondary strengthening using a high-temperature molten potassium nitrate and lithium nitrate mixture; Fourth, ultrasonic cleaning: Ultrasonic cleaning is performed on the microcrystalline glass that has undergone secondary strengthening. Secondary strengthening followed by pickling: The microcrystalline glass that has undergone secondary strengthening and ultrasonic cleaning is immersed in a strengthening acid solution, which is a mixture of hydrofluoric acid, hydrochloric acid, sulfuric acid and nitric acid. Fifth, ultrasonic cleaning: The microcrystalline glass that has undergone secondary strengthening and acid washing is then subjected to ultrasonic cleaning.

6. The microcrystalline glass processing and surface treatment process as described in claim 5, characterized in that, In the wire cutting step, a combination of 7µm or 12µm diamond wire and silicon carbide cutting fluid is used for wire cutting; In the pickling step after cutting, the hydrochloric acid solution contains 3%-15% hydrochloric acid by volume, and the soaking time is 3-15 minutes. In the CNC forming step, a suitable grinding head and NC program are selected for machining. Specifically, when rough machining the glass shape and chamfering, electroplated diamond grit of grade 300# to 400# is used, and when finishing the glass shape and chamfering, electroplated diamond grit of grade 1000# to 1500# is used. The concentricity of the grinding head is 0 to 0.01 mm. The feed rate of the NC program is 500 to 1000 mm / min, and the feed rate is 0.01 to 0.05 mm / pass. In the polishing and thinning step, a double-sided flat polishing machine is used, with polyurethane polishing skin or non-woven fabric polishing skin with a hardness of 70-83 applied to the upper and lower discs. The thickness of the polishing skin is 2.5-4.0 mm. A planetary wheel with a composite design of epoxy resin and steel plate is selected. The planetary wheel cavity is 0.05-0.25 mm larger than the microcrystalline glass on one side, and the planetary wheel thickness is 0.03-0.08 μm smaller than the microcrystalline glass. Cerium oxide polishing powder or aluminum oxide polishing powder is used. The particle size of the polishing powder is 1.2-1.5 μm, and the density of the polishing powder solution is 1.10-1.16 g / cm³. In the above-sweeping and below-polishing step, a double-sided flat polishing machine is used to sweep and grind the carpet from top to bottom. The upper plate is covered with a carpet with a pile length of 5-25mm, and the lower plate is covered with a polishing leather with a hardness of 70-83. The polishing leather is a polyurethane polishing leather or a non-woven fabric polishing leather with a thickness of 2.5-4.0mm. Cerium oxide polishing powder or aluminum oxide polishing powder is used, with a particle size of 1.0-1.5um and a solution density of 1.10-1.16g / cm³. In the edge polishing step, a brush wheel with a bristle length of 15-30 mm is selected, and the bristles are made of soft pig hair and / or horse hair. The polishing powder is cerium oxide or aluminum oxide with a particle size of 1.0-1.2 μm.

7. The microcrystalline glass processing and surface treatment process as described in claim 6, characterized in that, In the polishing and thinning step, the hardness of the polyurethane polishing skin or non-woven polishing skin is 73-82; the thickness of the planetary wheel is 0.03-0.05 mm smaller than that of the microcrystalline glass; and the density of the polishing powder is 1.12-1.14 g / cm³.

8. The microcrystalline glass processing and surface treatment process as described in claim 6, characterized in that, In the above sweeping and below polishing steps, the upper plate is used to apply a carpet with a pile length of 10-25mm, and the polishing powder has a particle size of 1.0-1.2um.

9. The microcrystalline glass processing and surface treatment process as described in claim 5, characterized in that, In the first ultrasonic cleaning step, the microcrystalline glass that has been polished by the side is placed in an oxalic acid solution tank or a citric acid solution tank at 30-35°C for ultrasonic cleaning. The mass concentration of the oxalic acid solution is ≤30%, and the mass concentration of the citric acid solution is ≤30%.

10. The microcrystalline glass processing and surface treatment process as described in claim 5, characterized in that, In the second ultrasonic cleaning step, a cleaning agent with a pH value of 8 to 10 is selected for ultrasonic cleaning. In the third ultrasonic cleaning step, a cleaning agent with a pH value of 8 to 10 is selected for ultrasonic cleaning. In the fourth ultrasonic cleaning step, a cleaning agent with a pH value of 8 to 10 is selected for ultrasonic cleaning. In the fifth ultrasonic cleaning step, a cleaning agent with a pH value of 8 to 10 is selected for ultrasonic cleaning.