CN112341164A

CN112341164A - Ceramic mold for glass hot bending molding and preparation method thereof

Info

Publication number: CN112341164A
Application number: CN202011166886.9A
Authority: CN
Inventors: 周遵光; 卓光进; 李振芳; 张荣兴; 林夕; 杨金城
Original assignee: Fuyao Glass Industry Group Co Ltd
Current assignee: Fuyao Group Shanghai Automotive Glass Co Ltd
Priority date: 2020-10-27
Filing date: 2020-10-27
Publication date: 2021-02-09
Anticipated expiration: 2040-10-27
Also published as: CN112341164B

Abstract

The application provides a ceramic mould for glass hot bending forming, which comprises the following raw materials in percentage by mass: corundum: 20% -80%; silicon carbide: 10% -35%; silicon oxide: 6 to 25 percent; calcium silicate: 1% -10%; adhesive: 1% -5%; dispersing agent: 1 to 5 percent. The ceramic mold has low thermal conductivity and low thermal expansion coefficient, can effectively reduce temperature fluctuation and expansion deformation of the mold in the use process, and can prepare the vehicle window glass with high shape precision, good optical performance and high structural strength. The ceramic die has the advantages of firm structure, good thermal shock resistance, difficult deformation and cracking in the long-term heating and cooling use process, and longer service life. The application also provides a preparation method of the ceramic mould for glass hot bending forming.

Description

Ceramic mold for glass hot bending molding and preparation method thereof

Technical Field

The application relates to the technical field of glass hot bending forming, in particular to a ceramic mold for glass hot bending forming and a preparation method thereof.

Background

The window glass is an important component of the automobile and is generally of a curved surface type structure, so the window glass needs to be subjected to hot bending forming to form a curved surface radian. The hot bending forming process comprises the steps of heating the flat glass to a softening temperature, then performing compression bending forming in a mold to obtain a specific shape, and then annealing to form the curved glass. In order to ensure the safety of automobile driving, the glass of the automobile window has high requirements on the radian of a curved surface and the optical performance.

At present, most of molds adopted by a glass hot bending forming process are metal molds, the thermal expansion coefficient of metal is large, expansion deformation can occur after the molds are heated, and further the problems of deformation, optical performance reduction and the like of pressed glass are caused, and the quality of products is reduced. On one hand, because the shape of the mold is not uniform, the temperature difference can be formed between the edge of the mold and the central area during heating, so that the problems of poor optical performance at the edge of the glass, unstable surface stress and the like are caused; on the other hand, because there is great difference in temperature in mould and ambient temperature (room temperature), the mould can continue to the external heat dissipation cooling, however when high temperature softening's glass and mould contact, the mould can absorb glass's heat again, leads to the mould temperature to rise, and the fluctuation of temperature can make the shape of mould constantly change, and then leads to the finished glass's curved surface radian and the undulant difference of optical property big, and the quality is unstable, is difficult to satisfy window glass's performance requirement. In the prior art, in order to compensate the heat loss of the contact between the glass and the mold and ensure the forming temperature of the glass, a method of raising the heating temperature of the glass is generally adopted, however, the raising of the temperature of the glass causes the glass to form more optical defects, and the optical performance is deteriorated, so the method is not suitable for preparing the window glass of the vehicle. In addition, the mould for hot bending the car window glass has large volume and area which can exceed 4.5m²The weight can reach 350kg, so that the high-strength high-thermal shock resistance die has high requirements on the performances of the die body, such as strength, thermal shock resistance and the like. Therefore, it is necessary to provide a ceramic mold for glass hot bending molding to solve the problems of expansion deformation, temperature fluctuation and poor thermal shock resistance of the existing mold for glass hot bending molding.

Disclosure of Invention

In order to solve the problems, the application provides a ceramic mold for glass hot bending molding, the ceramic mold has low thermal conductivity and low thermal expansion coefficient, temperature fluctuation and expansion deformation of the mold in the using process can be effectively reduced, and the vehicle window glass with high shape precision, good optical performance and high structural strength can be prepared. The ceramic die has the advantages of firm structure, good thermal shock resistance, no deformation and cracking in the long-term heating and cooling use process, and long service life.

The application provides in a first aspect a ceramic mould for glass hot bending, which is characterized in that the ceramic mould comprises the following raw materials in percentage by mass:

corundum: 20% -80%;

silicon carbide: 10% -35%;

silicon oxide: 6 to 25 percent;

calcium silicate: 1% -10%;

adhesive: 1% -5%;

dispersing agent: 1 to 5 percent.

The ceramic die adopts corundum, silicon oxide and calcium silicate with low thermal conductivity as raw materials, silicon carbide is added to enhance the structural strength of the ceramic die, and the corundum, the silicon carbide, the silicon oxide and the calcium silicate can form a crystalline phase with high strength and low thermal expansion coefficient by sintering the raw materials at high temperature. The dispersing agent can ensure that all components are uniformly distributed to form the ceramic mould with a stable structure. The adhesive can bond the raw material particles to promote the curing and forming of the ceramic mould. The ceramic die has low thermal conductivity and thermal expansion coefficient by combining the raw materials according to a specific proportion, can effectively reduce the temperature fluctuation and expansion deformation effect of the die in the using process, and can prepare the vehicle window glass with high shape precision, good optical performance and high structural strength.

Optionally, the corundum has a particle size of less than or equal to 1mm, and the corundum comprises at least two corundum powders with different particle size gradients.

Preferably, the corundum comprises three corundum powders with different particle size gradients in the following mass ratio, wherein the corundum powders are calculated by taking the total mass of the corundum as 100 percent:

corundum powder with the particle size of more than or equal to 0.1mm and less than 1 mm: 30% -80%;

corundum powder with the particle size of more than or equal to 0.05mm and less than 0.1 mm: 10% -35%;

corundum powder with the particle size of less than 0.05 mm: 10 to 35 percent.

Preferably, the corundum comprises four corundum powders with different particle size gradients in the following mass ratio, wherein the corundum powders are calculated by taking the total mass of the corundum as 100 percent:

optionally, the grain size of the silicon carbide is less than or equal to 1mm, and the silicon carbide includes at least two silicon carbide powders with different grain size gradients.

Preferably, the silicon carbide comprises silicon carbide powders with three different particle size gradients in the following mass ratio, wherein the total mass of the silicon carbide is 100%:

silicon carbide powder with the particle size of more than or equal to 0.1mm and less than 1 mm: 30% -80%;

silicon carbide powder with the particle size of more than or equal to 0.05mm and less than 0.1 mm: 10% -35%;

silicon carbide powder with the particle size of less than 0.05 mm: 10 to 35 percent.

Preferably, the silicon carbide comprises four silicon carbide powders with different particle size gradients in the following mass ratio, wherein the total mass of the silicon carbide is 100%:

silicon carbide powder having a particle diameter of 50 μm or more and less than 500 μm: 40% -70%;

silicon carbide powder with a particle size of 5 μm or more and less than 50 μm: 10% -30%;

silicon carbide powder with the particle size of more than or equal to 500nm and less than 5 mu m: 10% -30%;

silicon carbide powder with particle size less than 500 nm: 5 to 20 percent.

Optionally, the raw material of the ceramic mold further comprises 0.5-5% by mass of zirconium silicate.

Optionally, the binder includes one or more of hydrated corundum, sodium silicate, calcium aluminate, phenolic resin, epoxy resin, urethane resin, polyimide resin, and acrylic resin.

Optionally, the dispersant comprises one or more of oleic acid, stearic acid, polyethyleneimine, polyvinyl alcohol, polyethylene glycol, sodium lauryl sulfate, ammonium polyacrylate, guar gum, fatty acid polyglycol ester, acrylate, sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate.

Optionally, the thermal conductivity of the ceramic mold is less than or equal to 32 w/(m.k).

Optionally, the coefficient of thermal expansion of the ceramic mold is less than 5.2 × 10^-6/℃。

Optionally, the mass ratio of the corundum to the silicon carbide is 1: (0.14-1.6); the mass ratio of the corundum to the silicon oxide is 1: (0.1-1.2).

The ceramic mold for glass hot bending molding provided by the first aspect of the application has low thermal conductivity and thermal expansion coefficient, can effectively reduce temperature fluctuation and expansion deformation of the mold in the using process, and further improves the dimensional accuracy and optical performance of the vehicle window glass; the ceramic die has good thermal shock resistance, is not easy to deform and crack in the long-term heating and cooling use process, and has long service life.

The second aspect of the present application provides a method for preparing a ceramic mold for glass hot bending, comprising the steps of:

uniformly mixing the following raw materials in percentage by mass with water or an organic solvent to obtain ceramic slurry;

corundum: 20% -80%;

silicon carbide: 10% -35%;

silicon oxide: 6 to 25 percent;

calcium silicate: 1% -10%;

adhesive: 1% -5%;

dispersing agent: 1% -5%;

pouring the ceramic slurry into a mold, and drying to obtain a ceramic mold blank;

and sintering the ceramic mold blank at a high temperature to obtain the ceramic mold.

Optionally, the raw material further comprises 0.5-5% by mass of zirconium silicate.

Optionally, the temperature of the high-temperature sintering is 600 ℃ to 1400 ℃.

Optionally, the ceramic mold blank is sintered at a high temperature and then cooled to 25 ℃ at a cooling rate of not higher than 40 ℃/h.

Optionally, the high-temperature sintering includes: heating to the maximum of 150 ℃ at a heating rate of not higher than 20 ℃/h, heating to the maximum of 350 ℃ at a heating rate of not higher than 30 ℃/h, heating to the maximum of 600 ℃ at a heating rate of not higher than 30 ℃/h, heating to the maximum of 800 ℃ at a heating rate of not higher than 40 ℃/h, and heating to the maximum of 1400 ℃ at a heating rate of not higher than 40 ℃/h.

The preparation method of the ceramic mold for glass hot bending forming provided by the second aspect of the application is simple and convenient to operate and suitable for industrial mass production.

Detailed Description

The following is a preferred embodiment of the present application, and it should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present application, and these improvements and modifications are also considered as the protection scope of the present application.

The application provides a ceramic mould for glass hot bending, and the ceramic mould comprises the following raw materials in percentage by mass:

corundum: 20% -80%;

silicon carbide: 10% -35%;

silicon oxide: 6 to 25 percent;

calcium silicate: 1% -10%;

adhesive: 1% -5%;

dispersing agent: 1 to 5 percent.

In the application, the corundum is added to reduce the thermal conductivity of the ceramic mold and enhance the heat insulation performance of the mold, so that the expansion deformation of the mold due to temperature fluctuation is reduced. In some embodiments of the present application, the corundum is brown corundum. In the embodiment of the application, the mass percentage of the corundum is 20-80%. In some embodiments of the present disclosure, the corundum is 30% to 60% by weight. The mass percentage content of corundum may be, but not limited to, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80%. The mass content of the corundum is controlled within a proper range, so that the heat conductivity of the ceramic material can be reduced, the heat insulation performance of a ceramic mold is enhanced, the absorption of glass heat in the production process is reduced, the temperature fluctuation of the mold is reduced, and the produced glass has stable optical performance; on the other hand, the corundum has lower cost, and the cost of the ceramic die can be reduced by using the corundum.

In the embodiment of the application, the grain size of the raw material particles is controlled to be moderate, the separation area of a grain boundary and an air hole is reduced, the sintering temperature is reduced, the abnormal growth of the grains can be reduced, and the grains of the ceramic body are uniformly distributed, so that the heat conductivity of the ceramic is reduced, and the structural strength of the ceramic mold is improved. In an embodiment of the present application, the corundum has a particle size of 1mm or less. Specifically, the corundum may be formed by mixing two or more kinds of corundum powders with different particle size gradients, wherein the particle size gradient range and the gradient number of the corundum powders can be adjusted as required, and the particle size gradient range can be defined as a first gradient particle size, a second gradient particle size, a third gradient particle size, a fourth gradient particle size, a fifth gradient particle size and the like in sequence according to the arrangement of the particle size gradient range from large to small. Through particle grade pairing of the corundum, the stacking density of particles in the ceramic mold can be increased, and gaps among the particles are reduced, so that the ceramic mold has lower thermal conductivity and thermal expansion coefficient and good thermal shock resistance.

In some embodiments of the present application, the corundum is obtained by mixing three corundum powders with gradient particle sizes, specifically, the first gradient particle size is greater than or equal to 100 μm and less than 1mm, the second gradient particle size is greater than or equal to 50 μm and less than 100 μm, and the third gradient particle size is less than 50 μm, wherein the corundum powder with the first gradient particle size accounts for 30-80% by mass of the corundum, the corundum powder with the second gradient particle size accounts for 10-35% by mass of the corundum, and the corundum powder with the third gradient particle size accounts for 10-35% by mass of the corundum. In other embodiments of the present application, the first gradient particle size is greater than or equal to 50 μm and less than 500 μm, the second gradient particle size is greater than or equal to 5 μm and less than 50 μm, and the third gradient particle size is less than 5 μm, wherein the corundum powder of the first gradient particle size accounts for 50% to 80% by mass of the corundum, the corundum powder of the second gradient particle size accounts for 10% to 30% by mass of the corundum, and the corundum powder of the third gradient particle size accounts for 10% to 30% by mass of the corundum.

In other embodiments of the present application, the corundum is obtained by mixing four kinds of corundum powder with gradient particle size, wherein the first gradient particle size is greater than or equal to 50 μm and less than 500 μm, the second gradient particle size is greater than or equal to 5 μm and less than 50 μm, the third gradient particle size is greater than or equal to 500nm and less than 5 μm, and the fourth gradient particle size is less than 500nm, wherein the corundum powder with the first gradient particle size accounts for 40-70% of the corundum by mass, the corundum powder with the second gradient particle size accounts for 10-30% of the corundum by mass, the corundum powder with the third gradient particle size accounts for 10-30% of the corundum by mass, and the corundum powder with the fourth gradient particle size accounts for 5-20% of the corundum by mass.

In this application, add carborundum and can reduce ceramic mold's coefficient of thermal expansion to promote the structural strength and the wear resistance of mould, prolong the life of mould. In the embodiment of the application, the mass percentage of the silicon carbide is 10-35%. In the embodiment of the application, the mass ratio of corundum to silicon carbide is 1: (0.14-1.6), and further, the mass ratio of corundum to silicon carbide is 1: (0.3-1.5). In some embodiments of the present application, the mass ratio of corundum to silicon carbide is 1: (0.4-1). The mass ratio of the corundum to the silicon carbide is controlled, so that the ceramic die has low thermal expansion coefficient and low thermal conductivity, has good wear resistance and prolongs the service life of the die. In some embodiments of the present disclosure, the silicon carbide is 20% to 30% by mass. The content of silicon carbide may be, but not limited to, 10%, 15%, 17%, 20%, 22%, 25%, 30%, 33%, or 35% by mass. The quality percentage content of the silicon carbide is controlled, so that the ceramic die has lower heat conductivity, and the temperature fluctuation of the die in the use process is reduced.

In the embodiment of the application, the heat conductivity of the ceramic die can be adjusted by controlling the particle size distribution of the raw material particles, and the heat transfer performance of the ceramic die is improved. In the embodiments of the present application, the particle size of silicon carbide is 1mm or less. In the embodiment of the present application, the silicon carbide may be formed by mixing two or more silicon carbide powders with different particle size gradients, and the specific particle size gradient classification method is the same as that adopted for corundum, and is not described herein again. Through carrying out particle grade pairing on the silicon carbide, the stacking density of the ceramic mold can be increased, gaps among particles are reduced, the stacking density of the particles is improved, and the ceramic mold has lower thermal expansion coefficient and thermal shock resistance.

In some embodiments of the present application, the silicon carbide is obtained by mixing silicon carbide powders with three particle size gradients, specifically, the first gradient particle size is greater than or equal to 100 μm and less than 1mm, the second gradient particle size is greater than or equal to 50 μm and less than 100 μm, and the third gradient particle size is less than 50 μm, where the mass percentage of the silicon carbide powder with the first gradient particle size in the silicon carbide is 30% -80%, the mass percentage of the silicon carbide powder with the second gradient particle size in the silicon carbide is 10% -35%, and the mass percentage of the silicon carbide powder with the third gradient particle size in the silicon carbide is 10% -35%. In other embodiments of the present application, the first gradient particle size is greater than or equal to 50 μm and less than 500 μm, the second gradient particle size is greater than or equal to 5 μm and less than 50 μm, and the third gradient particle size is less than 5 μm, wherein the silicon carbide powder with the first gradient particle size accounts for 50% to 80% by mass of the silicon carbide, the silicon carbide powder with the second gradient particle size accounts for 10% to 30% by mass of the silicon carbide, and the silicon carbide powder with the third gradient particle size accounts for 10% to 30% by mass of the silicon carbide.

In other embodiments of the present application, the silicon carbide is obtained by mixing four silicon carbide powders with different particle size gradients, where a first gradient particle size is greater than or equal to 50 μm and less than 500 μm, a second gradient particle size is greater than or equal to 5 μm and less than 50 μm, a third gradient particle size is greater than or equal to 500nm and less than 5 μm, and a fourth gradient particle size is less than 500nm, where the silicon carbide powder with the first gradient particle size accounts for 40-70% by mass of the silicon carbide, the silicon carbide powder with the second gradient particle size accounts for 10-30% by mass of the silicon carbide, the silicon carbide powder with the third gradient particle size accounts for 10-30% by mass of the silicon carbide, and the silicon carbide powder with the fourth gradient particle size accounts for 5-20% by mass of the silicon carbide.

In this application, silicon oxide can form the glass phase in ceramic mold sintering process, is favorable to raw materials granule intensive mixing dispersion on the one hand, and on the other hand silicon oxide can produce the glaze layer on ceramic mold surface, improves the smooth finish on mould surface, avoids the mould to produce the trace on the glass surface at the in-process of preparation car window glass. In the embodiment of the present application, the particle size of the silicon oxide is 200um or less. In some embodiments of the present application, the silica has a particle size of less than or equal to 50 um. The particle size of the silicon oxide may specifically be, but not limited to, 10nm, 100nm, 1um, 5um, 10um, 20um, 30um, 40um, 50um, 100um, or 200 um. In some embodiments of the present disclosure, the silica has a median particle size D50 of 5um to 15 um. The median particle diameter D50 of the silicon oxide may specifically be, but is not limited to, 5um, 7um, 8.5um, 9um, 10um, 11um, or 15 um. In the application, the thermal conductivity of the ceramic mold can be reduced by controlling the content of the silicon oxide. In the embodiment of the application, the mass percentage of the silicon oxide is 6-25%. The content of the silicon oxide may be, but not limited to, 6%, 8%, 10%, 15%, 17%, 20%, 23%, or 25% by mass. In the application, part of corundum and silicon oxide in the raw materials can form mullite with low heat conductivity and thermal expansion coefficient in the high-temperature sintering process, so that the structural strength and the thermal stability of the ceramic mold are improved. In the embodiment of the application, the mass ratio of corundum to silicon oxide is 1: (0.1-1.2), and further, the mass ratio of corundum to silicon oxide is 1: (0.14-0.67).

In the application, the calcium silicate can be filled among the raw materials, so that the raw materials can be fully dispersed in the ceramic slurry, and the uniform stability of the die is improved; in the high-temperature sintering process, the calcium silicate can eliminate fine micropores in the ceramic mould, so that the thermal conductivity and the thermal expansion coefficient of the ceramic mould are reduced. In an embodiment of the present application, the calcium silicate has a particle size of 1mm or less. In the application, the calcium silicate content can reduce the volume effect of calcium silicate phase change in a proper range, so that the volume stability of the ceramic die is ensured. In the embodiment of the application, the mass percentage of the calcium silicate is 1-10%. The calcium silicate may be contained in an amount of 1%, 3%, 5%, 6%, 8%, 9% or 10% by mass, though not limited thereto.

In the application, corundum, silicon oxide, silicon carbide and calcium silicate are easy to agglomerate in a liquid-phase medium due to large specific surface area, especially when the solid content is high, the average distance among particles is reduced, and the probability of agglomeration caused by particle collision is greatly increased, so that the dispersibility, stability and uniformity of the ceramic slurry are influenced. The dispersing agent is added to prevent raw material particles from agglomerating, so that all components are uniformly dispersed, and meanwhile, the dispersing agent can improve the fluidity of a raw material mixture, so that the ceramic slurry is fully filled into a mold, the formed ceramic mold is guaranteed to be complete in structure, and excellent mold technological properties are obtained. In an embodiment of the present application, the dispersant includes one or more of oleic acid, stearic acid, polyethyleneimine, polyvinyl alcohol, polyethylene glycol, sodium lauryl sulfate, ammonium polyacrylate, guar gum, fatty acid polyglycol ester, acrylate, sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate. In some embodiments of the present application, the dispersant comprises one or more organic dispersants selected from the group consisting of oleic acid, stearic acid, polyethyleneimine, polyvinyl alcohol, polyethylene glycol, sodium lauryl sulfate, ammonium polyacrylate, guar gum, fatty acid polyethylene glycol esters, and acrylates. The organic dispersing agent can be carbonized in the sintering process of the die, and cannot influence the formation of crystalline phases in the ceramic die, so that the structural strength and the service life of the ceramic die are ensured. In some embodiments of the present disclosure, the dispersant is present in an amount of 1% to 5% by weight. The content of the dispersant may be specifically, but not limited to, 1%, 2%, 3%, or 5% by mass.

In the application, the adhesive can be adhered to the surfaces of the raw material particles, so that the raw material particles with different particle sizes are bonded together, the particles are prevented from being aggregated, and the ceramic mould is promoted to be cured and molded. In embodiments of the present application, the binder includes one or more of hydrated corundum, sodium silicate, calcium aluminate, phenolic resin, epoxy resin, urethane resin, polyimide resin, and acrylic resin. The adhesive has low thermal expansion coefficient, can reduce ceramic defects generated by thermal stress in the sintering process, and is beneficial to improving the stability of a ceramic die. In the embodiment of the application, the mass percentage of the adhesive is 1-5%. The content of the binder may be, but not limited to, 1%, 2%, 3%, or 5% by mass.

In some embodiments of the present application, the raw material of the ceramic mold further comprises zirconium silicate. The zirconium silicate is added, so that a certain amount of zirconium oxide crystals can be formed in the sintering process of the ceramic mold, the zirconium oxide crystals have higher thermal expansion coefficient, the zirconium oxide crystals can expand in the sintering and subsequent use processes of the ceramic mold to form micro cracks on the periphery, the micro cracks can effectively disperse stress generated by the thermal shock of the mold, relieve main cracks generated by the thermal shock of the mold, absorb energy of the main cracks, decompose the main cracks into a plurality of fine cracks, and prevent the further development of the main cracks, so that the thermal shock resistance of the ceramic mold is improved. In addition, zirconium silicate can react with corundum to generate aluminum zirconate, and the aluminum zirconate can also improve the strength of the ceramic mold. In the embodiment of the present application, the mass percentage of zirconium silicate is 0.5% to 5%, and the mass percentage of zirconium silicate may be specifically, but not limited to, 0.5%, 1%, 2%, 3%, or 5%. The control of the content of zirconium silicate can ensure the low thermal conductivity and thermal expansion coefficient of the ceramic mould, improve the toughness of the ceramic mould, enhance the thermal shock resistance of the ceramic mould and enable the ceramic mould to be used for a long time at high temperature.

In the embodiment of the present application, the thermal conductivity of the ceramic mold is not more than 32w/(m.k), and the thermal expansion coefficient of the ceramic mold is not more than 5.2 × 10^-6V. C. The ceramic mold with low thermal conductivity and thermal expansion coefficient can effectively reduce the mold temperature fluctuation and the mold shape fluctuation in the production process and the re-production after production pause, and improve the shape precision, the optical performance and the quality stability of the car window glass; meanwhile, the ceramic mold can be heated to a higher temperature due to low thermal conductivity, so that the heat loss of glass when the glass contacts the mold is reduced, the heating temperature of the glass before molding is reduced, the optical defects of the window glass are reduced, and the optical performance of the window glass is improved.

In the embodiment of the application, the compressive strength of the ceramic mould is greater than or equal to 70 Mpa.

According to the preparation method, the corundum, the silicon carbide, the silicon oxide and the calcium silicate in a certain ratio are adopted to prepare the ceramic mold with low thermal conductivity and low thermal expansion coefficient, the ceramic mold has high compactness and strong thermal shock resistance by controlling the particle size and distribution of raw materials, the ceramic mold can effectively reduce the temperature fluctuation and expansion deformation effect of the mold in the using process, and the vehicle window glass with high shape precision, good optical performance and high structural strength can be prepared. Meanwhile, the ceramic die has good thermal shock resistance, can not deform and crack in the long-term heating and cooling use process, and has long service life.

The application also provides a preparation method of the ceramic mould for glass hot bending forming, which comprises the following steps:

s01: uniformly mixing the following raw materials in percentage by mass with water or an organic solvent to obtain ceramic slurry;

corundum: 20% -80%;

silicon carbide: 10% -35%;

silicon oxide: 6 to 25 percent;

calcium silicate: 1% -10%;

adhesive: 1% -5%;

dispersing agent: 1% -5%;

s02: pouring the ceramic slurry into a mold, drying and demolding to obtain a ceramic mold blank;

s03: and sintering the ceramic mold blank at a high temperature to obtain the ceramic mold.

In the embodiment of the present application, in step S01, the mixing may be stirring, and the stirring time is 1 to 10min, and the stirring time may be, but is not limited to, 1min, 3min, 5min, or 10 min. The stirring time is controlled to ensure that the ceramic slurry has good fluidity and dispersibility, so that the female die of the die can be fully filled with the ceramic slurry, and the ceramic slurry effectively prevents raw material particles from precipitating. In the embodiment of the present application, the solvent used for mixing the raw materials includes water or an organic solvent. The ceramic slurry prepared by mixing the raw materials and the solvent can adjust the fluidity and the component uniformity of the slurry, and is beneficial to forming a ceramic mold with a stable structure. In some embodiments, the organic solvent includes one or more of ethanol, propanol, acetone, acetylacetone, acetoacetyl ester, and acetylacetone. In the embodiment of the present application, the mass of the added solvent is less than or equal to 10% of the mass of the raw material. The addition of a certain amount of water into the ceramic slurry can improve the structural strength of the ceramic slurry in the curing process, and is beneficial to smooth demolding of the ceramic mold blank. In the embodiment of the present application, the mixing device includes any one of a mixer, a ball mill, a blender or a kneader.

In the embodiment of the present application, in step S02, when the ceramic slurry is poured into the mold, the adhesive will continue to react until the ceramic slurry is cured, so that the ceramic mold has a certain initial strength, thereby facilitating the demolding and subsequent processing of the mold, and the processing specifically includes cutting, drilling, or installing other components. In this application embodiment, when the mould was poured into to ceramic slurry, the mould can vibrate to gas in the discharge slurry guarantees ceramic mould's homogeneity and compactness. In the embodiment of the application, the surface of the mold is sprayed with the release agent in advance, wherein the release agent comprises one or more of fatty acid soap, fatty acid, paraffin, glycerol, vaseline, silicone oil, polyethylene glycol, polyethylene, talcum powder and mica powder. In the embodiment of the application, the ceramic mold is dried under the condition of natural drying or drying at the temperature of not higher than 150 ℃. When the drying condition is drying, the solvent can be completely removed at the drying temperature of 150 ℃; when the drying condition is natural drying, the solvent can be completely removed in the early stage of the natural drying process and high-temperature sintering.

In the embodiment of the present application, in step S03, the temperature of the high-temperature sintering is 600 ℃ to 1400 ℃.

In some embodiments of the present application, the conditions for high temperature sintering are multi-stage temperature programming:

first-stage heating: heating at a temperature range of less than or equal to 150 ℃ at a heating rate of not more than 20 ℃/h, and carrying out heat preservation treatment for 12-30 h when the temperature reaches the temperature in the temperature range, and further carrying out heat preservation for 20-24 h;

second-stage heating: heating at a temperature range of more than 150 ℃ and less than or equal to 350 ℃ at a heating rate of not more than 30 ℃/h, and carrying out heat preservation treatment for 12-30 h when the temperature reaches the temperature in the temperature range, and further carrying out heat preservation for 20-24 h;

third-stage heating: heating at a temperature range of more than 350 ℃ and less than or equal to 600 ℃ at a heating rate of not more than 30 ℃/h, and carrying out heat preservation treatment for 12h-24h when the temperature reaches the temperature in the temperature range, and further carrying out heat preservation for 14h-16 h;

and (3) heating in the fourth stage: heating at a temperature range of more than 600 ℃ and less than or equal to 800 ℃ at a heating rate of not more than 40 ℃/h, and carrying out heat preservation treatment for 12h-24h when the temperature reaches the temperature in the temperature range, and further carrying out heat preservation for 14h-16 h;

fifth stage heating: heating at a temperature range of more than 800 ℃ and less than or equal to 1400 ℃ at a heating rate of not more than 40 ℃/h, and when the temperature reaches the temperature in the temperature range, carrying out heat preservation treatment for 12h-30h, and further carrying out heat preservation for 20-24 h.

In some embodiments of the present disclosure, the ceramic mold is obtained by performing temperature programmed sintering in the first, second, third, and fourth stages. In other embodiments of the present application, the ceramic mold is obtained by performing temperature programmed sintering in the first, second, third, fourth, and fifth stages. In some embodiments of the present application, the fourth temperature programming is performed at a temperature rate of not more than 30 ℃/h.

And (3) after the ceramic die blank is sintered at high temperature, cooling to 15-30 ℃ at a cooling rate of not higher than 40 ℃/h to obtain the ceramic die. The ceramic die can have larger and more network structure crystals by controlling the sintering conditions of the ceramic die blank, and the network structure crystals can relieve the impact of volume change caused by the crystallization or phase change of ceramic components in the processes of heating and cooling of ceramic (the ceramic components comprise various ceramic raw materials prepared by the ceramic die, various new components generated in the sintering process such as mullite, anorthite and the like, and crystals with different structures generated by the crystal phase conversion in the sintering and cooling process), so that the strength of the ceramic die is improved.

The preparation method of the ceramic mould for glass hot bending forming is simple in condition and suitable for industrial production.

The application also provides a glass hot bending forming machine, which comprises a conveying device, a preheating device, a glass hot bending device and an annealing device, wherein the glass hot bending device comprises the ceramic mold.

The following further describes embodiments of the present application in terms of several examples.

Example 1:

a ceramic mould for glass hot bending molding and a preparation method thereof are disclosed, wherein the ceramic mould is composed of raw materials with mass ratios shown in Table 1.

Table 1 example 1 ceramic mold stock composition

Corundum: 50 percent of	Silicon carbide: 20 percent of
		Silicon oxide: 10 percent of	Calcium silicate: 10 percent of
Polyvinyl alcohol: 5 percent of	Phenolic resin: 5 percent of

Wherein, the corundum and the silicon carbide are obtained by mixing corundum powder or silicon carbide powder with different grain diameter gradients, and the specific grain diameter gradients and contents are shown in tables 2 and 3.

Table 2 example 1 composition of corundum

Grain size range of corundum powder	Content (wt.)
		Greater than or equal to 100 μm and less than 1mm	50％
50 μm or more and less than 100 μm	35％
		Less than 50 μm	15％

Table 3 example 1 composition of silicon carbide

Particle size range of silicon carbide powder	Content (wt.)
		Greater than or equal to 100 μm and less than 1mm	60％
50 μm or more and less than 100 μm	20％
		Less than 50 μm	20％

The preparation method of the ceramic mould comprises the following steps:

1) preparing ceramic slurry: adding corundum, silicon carbide, silicon oxide, calcium silicate, polyvinyl alcohol and phenolic resin into a mixer for mixing, and then adding water for mixing to obtain ceramic slurry. Wherein the water addition amount is 7 percent of the total weight of the raw materials, and the stirring time is 3 min.

2) Pouring: pouring the ceramic slurry into the female mold with silicone oil coated surface, and drying to obtain the ceramic mold blank.

3) And (3) sintering: sintering the ceramic die blank at high temperature in a sintering furnace, wherein the sintering temperature conditions are as follows: heating to 150 ℃ at the heating rate of 15 ℃/h, and keeping the temperature for 24 h; heating to 350 ℃ at the heating rate of 20 ℃/h, and keeping the temperature for 24 h; heating to 550 ℃ at the heating rate of 25 ℃/h, and keeping the temperature for 16 h; heating to 680 ℃ at the heating rate of 30 ℃/h; cooling to 25 ℃ at the cooling rate of 35 ℃/h to obtain the ceramic die.

Example 2:

a ceramic mould for glass hot bending molding and a preparation method thereof are disclosed, wherein the ceramic mould is composed of raw materials with mass ratio shown in Table 4.

Table 4 example 2 ceramic mold stock composition

Corundum: 70 percent of	Silicon carbide: 10 percent of
		Silicon oxide: 10 percent of	Calcium silicate: 5 percent of
Sodium lauryl sulfate: 2 percent of	Sodium silicate: 3 percent of

Wherein, the corundum is obtained by mixing corundum powders with different grain diameter gradients, and the specific grain diameter gradients and contents are shown in table 5.

Table 5 composition of corundum according to example 2

Grain size range of corundum powder	Content (wt.)
		Greater than or equal to 500 μm and less than 1mm	50％
50 μm or more and less than 500 μm	20％
		Greater than or equal to 500nm and less than 50 μm	20％
Less than 500nm	10％

The preparation method of the ceramic mould comprises the following steps:

1) preparing ceramic slurry: adding corundum, silicon carbide, silicon oxide, calcium silicate, sodium dodecyl sulfate and sodium silicate into a stirrer for mixing, and then adding ethanol for mixing to obtain ceramic slurry. Wherein the weight of the added ethanol is 3 percent of the total weight of the raw materials, and the stirring time is 1 min.

3) And (3) sintering: sintering the ceramic die blank at high temperature in a sintering furnace, wherein the sintering temperature conditions are as follows: heating to 150 ℃ at the heating rate of 20 ℃/h, and keeping the temperature for 24 h; heating to 350 ℃ at the heating rate of 15 ℃/h, and keeping the temperature for 24 h; heating to 600 ℃ at the heating rate of 25 ℃/h, and keeping the temperature for 16 h; heating to 800 ℃ at the heating rate of 30 ℃/h, and keeping the temperature for 16 h; heating to 1000 ℃ at the heating rate of 30 ℃/h, and keeping the temperature for 16 h; cooling to 20 ℃ at a cooling rate of 20 ℃/h to obtain the ceramic die.

Example 3:

a ceramic mould for glass hot bending molding and a preparation method thereof are disclosed, wherein the ceramic mould is composed of raw materials with mass ratio shown in Table 6.

Table 6 example 3 ceramic mold stock composition

Corundum: 30 percent of	Silicon carbide: 30 percent of
		Silicon oxide: 20 percent of	Calcium silicate: 10 percent of
Oleic acid: 5 percent of	Epoxy resin: 5 percent of

Wherein, the corundum and the silicon carbide are obtained by mixing corundum powder or silicon carbide powder with different grain diameter gradients, and the specific grain diameter gradients and contents are shown in tables 7 and 8.

Table 7 example 3 composition of corundum

Grain size range of corundum powder	Content (wt.)
		50 μm or more and less than 500 μm	40％
Greater than or equal to 5 μm and less than 50 μm	30％
		Less than 5 μm	30％

Table 8 example 3 composition of silicon carbide

Particle size range of silicon carbide powder	Content (wt.)
		50 μm or more and less than 500 μm	50％
Greater than or equal to 5 μm and less than 50 μm	20％
		Greater than or equal to 500nm and less than 5 μm	20％
Less than 500nm	10％

The preparation method of the ceramic mould comprises the following steps:

1) preparing ceramic slurry: adding corundum, silicon carbide, silicon oxide, calcium silicate, oleic acid and epoxy resin into a mixer for mixing, and then adding acetone for mixing to obtain ceramic slurry. Wherein the weight of the added acetone is 6 percent of the total weight of the raw materials, and the stirring time is 4 min.

3) And (3) sintering: sintering the ceramic die blank at high temperature in a sintering furnace, wherein the sintering temperature conditions are as follows: heating to 130 ℃ at the heating rate of 5 ℃/h, and keeping the temperature for 24 h; heating to 350 ℃ at the heating rate of 15 ℃/h, and keeping the temperature for 24 h; heating to 500 ℃ at the heating rate of 20 ℃/h, and keeping the temperature for 16 h; heating to 800 ℃ at the heating rate of 25 ℃/h, and keeping the temperature for 16 h; heating to 1400 ℃ at the heating rate of 25 ℃/h, and keeping the temperature for 24 h; cooling to 25 ℃ at the cooling rate of 40 ℃/h to obtain the ceramic die.

Example 4

The ceramic mold consists of raw materials in mass ratio shown in table 9 and is prepared according to the requirement of the molded surface curvature of a test product.

Table 9 example 4 ceramic mold stock composition

Corundum: 68 percent of	Silicon carbide: 10 percent of
		Silicon oxide: 10 percent of	Calcium silicate: 5 percent of
Sodium lauryl sulfate: 2 percent of	Polyurethane resin: 3 percent of
		Zirconium silicate: 2 percent of

Wherein, the corundum and the silicon carbide are obtained by mixing corundum powder or silicon carbide powder with different grain diameter gradients, and the specific grain diameter gradients and contents are shown in tables 10 and 11.

TABLE 10 composition of corundum of example 4

Table 11 example 4 composition of silicon carbide

Particle size range of silicon carbide powder	Content (wt.)
		50 μm or more and less than 500 μm	30％
Greater than or equal to 5 μm and less than 50 μm	35％
		Less than 5 μm	35％

The preparation method of the ceramic mould comprises the following steps:

1) preparing ceramic slurry: adding corundum, silicon carbide, silicon oxide, calcium silicate, zirconium silicate, sodium dodecyl sulfate and polyurethane resin into a mixer for mixing, and then adding propanol for mixing to obtain ceramic slurry. Wherein the weight of the added propanol is 1 percent of the total weight of the raw materials, and the stirring time is 3 min.

3) And (3) sintering: sintering the ceramic die blank at high temperature in a sintering furnace, wherein the sintering temperature conditions are as follows: heating to 100 ℃ at the heating rate of 10 ℃/h, and keeping the temperature for 24 h; heating to 300 ℃ at the heating rate of 20 ℃/h, and keeping the temperature for 24 h; heating to 550 ℃ at the heating rate of 25 ℃/h, and keeping the temperature for 16 h; heating to 800 ℃ at the heating rate of 30 ℃/h, and keeping the temperature for 16 h; heating to 1200 ℃ at the heating rate of 30 ℃/h, and keeping the temperature for 20 h; cooling to 20 ℃ at the cooling rate of 30 ℃/h to obtain the ceramic die.

Effects of the embodiment

In order to verify the performance of the ceramic mould for glass hot bending forming, the application also provides an effect embodiment.

(1) The density of the ceramic mold was measured using the method GB/T25995-2010, and the results are shown in Table 12.

(2) The thermal conductivity of the ceramic mold was measured using the ISO 22007-2:2008 method, see table 12 for the results.

(3) The thermal expansion coefficient of the ceramic mold was measured using the method GB/T16535-.

(4) The ceramic molds of examples 1-4 were tested for thermal shock resistance. The specific process is as follows: heating the sample to 1100 ℃ in a muffle furnace, taking out the sample, cooling the sample in air for 5min, putting the sample into water at 25 ℃, repeatedly heating and cooling the ceramic mold for 15 times, and observing the cracking condition of the ceramic mold. See table 12 for results.

(5) The ceramic mold of example 4 was subjected to a production stability test. The procedure for the production stability test was: the ceramic die is installed on equipment for actual production, a certain number of continuously produced glass finished products are selected, and the surface stress, the optical performance and the spherical surface precision of the glass finished products are detected.

Specifically, the surface stress test of the glass finished product is to select 5 detection points at different positions on the glass finished product, wherein the detection point 5 is a product center, the detection points 1-4 are respectively surface stress detection values of 4 edges of the product, and the detection values of the detection points 1-4 are values with the largest difference from the detection value of the detection point 5 on the edge. The surface stress detection instrument is LCD-Gasp (produced by Streptotics, USA), the detection method is ASTM C1279, and the product surface stress requirement is 90Mpa-140 Mpa. See table 13 for the surface stress test results of the glass product.

The optical properties of the finished glass product were measured by a Moore scanner (manufactured by Isra, Switzerland) according to the standards of the automotive host factory, and the optical requirements of the finished glass product were as follows: the optical maximum value is less than or equal to 100mdpt, and the optical range difference value is less than or equal to 125 mpdt. The spherical surface is the maximum falling depth of the product, and the standard of the product is 13 plus or minus 2mm by detecting with a dial indicator. The optical properties of the finished glass products are shown in Table 14.

TABLE 12 table of performance parameters for ceramic molds made in examples 1-4

	Density (%)	Thermal conductivity (W/m. K)	Coefficient of thermal expansion (/ deg.C)	Thermal shock resistance
					Example 1	98.5	23.95	5.1×10^-6	Not cracking
Example 2	97.4	14.88	4.6×10^-6	Not cracking
					Example 3	99.2	30.22	3.9×10^-6	Not cracking
Example 4	97.1	15.01	4.2×10^-6	Not cracking

As can be seen from the test results in table 12, the ceramic mold for glass hot bending provided in the embodiment of the present application has low thermal conductivity and thermal expansion coefficient, higher compactness, and good thermal shock resistance.

TABLE 13 Table of parameters of surface stress of glass products produced by ceramic molds made in example 4

As can be seen from the test results in table 13, the surface stress of the glass product continuously produced by the ceramic mold provided in the embodiment of the present application not only meets the standard requirements of the product, but also the surface stress of different products sequentially produced at different positions of the product is very stable.

TABLE 14 optical Properties and sphere accuracy parameter Table for glass products produced by the ceramic mold obtained in example 4

As can be seen from the test results in table 14, the optical performance and spherical accuracy of the glass product continuously produced by the ceramic mold provided in the embodiment of the present application are very excellent, and not only the standard requirements of the product are met, but also the optical performance and spherical accuracy of different products produced sequentially are very stable.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The ceramic mold for glass hot bending molding is characterized by comprising the following raw materials in percentage by mass:

corundum: 20% -80%;

silicon carbide: 10% -35%;

silicon oxide: 6 to 25 percent;

calcium silicate: 1% -10%;

adhesive: 1% -5%;

dispersing agent: 1 to 5 percent.

2. The ceramic mold of claim 1, wherein the corundum has a grain size of less than or equal to 1mm, the corundum including corundum powders of at least two different grain size gradients.

3. The ceramic mold according to claim 2, wherein the corundum comprises corundum powder with three different particle size gradients in the following mass ratio, based on 100% of the total mass of the corundum:

corundum powder with the particle size of less than 0.05 mm: 10 to 35 percent.

4. The ceramic mold according to claim 2, wherein the corundum comprises four corundum powders with different particle size gradients in the following mass ratio, based on 100% of the total mass of the corundum:

5. the ceramic mold of claim 1, wherein the silicon carbide has a grain size of less than or equal to 1mm, and the silicon carbide comprises at least two silicon carbide powders having different grain size gradients.

6. The ceramic mold according to claim 5, wherein the silicon carbide comprises silicon carbide powders with three different particle size gradients in the following mass ratio, based on 100% of the total mass of the silicon carbide:

7. The ceramic mold according to claim 5, wherein the silicon carbide comprises four silicon carbide powders with different particle size gradients in the following mass ratio, based on 100% of the total mass of the silicon carbide:

silicon carbide powder with particle size less than 500 nm: 5 to 20 percent.

8. The ceramic mold according to claim 1, wherein the raw material of the ceramic mold further comprises 0.5 to 5 mass% of zirconium silicate.

9. The ceramic mold of claim 1, wherein the binder comprises one or more of hydrated corundum, sodium silicate, calcium aluminate, phenolic resin, epoxy resin, polyurethane resin, polyimide resin, and acrylic resin; the dispersing agent comprises one or more of oleic acid, stearic acid, polyethyleneimine, polyvinyl alcohol, polyethylene glycol, sodium dodecyl sulfate, ammonium polyacrylate, guar gum, fatty acid polyethylene glycol ester, acrylate, sodium tripolyphosphate, sodium hexametaphosphate and sodium pyrophosphate.

10. The ceramic mold of claim 1, wherein the ceramic mold has a thermal conductivity of less than or equal to 32 w/(m.k); the coefficient of thermal expansion of the ceramic mould is less than 5.2 multiplied by 10^-6/℃。

11. The ceramic mold of claim 1, wherein the mass ratio of the corundum to the silicon carbide is 1: (0.14-1.6); the mass ratio of the corundum to the silicon oxide is 1: (0.1-1.2).

12. A preparation method of a ceramic mould for glass hot bending forming is characterized by comprising the following steps:

corundum: 20% -80%;

silicon carbide: 10% -35%;

silicon oxide: 6 to 25 percent;

calcium silicate: 1% -10%;

adhesive: 1% -5%;

dispersing agent: 1% -5%;

13. The method of claim 12, wherein the feedstock further comprises zirconium silicate in an amount of 0.5% to 5% by weight.

14. The method of claim 12, wherein the high temperature sintering is at a temperature of 600 ℃ to 1400 ℃; and cooling the ceramic mold blank to 25 ℃ at a cooling speed of not higher than 40 ℃/h after high-temperature sintering.

15. The method of claim 12, wherein the high temperature sintering comprises: heating to the maximum of 150 ℃ at a heating rate of not higher than 20 ℃/h, heating to the maximum of 350 ℃ at a heating rate of not higher than 30 ℃/h, heating to the maximum of 600 ℃ at a heating rate of not higher than 30 ℃/h, heating to the maximum of 800 ℃ at a heating rate of not higher than 40 ℃/h, and heating to the maximum of 1400 ℃ at a heating rate of not higher than 40 ℃/h.