alumina grinding ball production and application

Ball mill is widely used in metallurgy, mineral, power, building materials, chemical and other fields, is the most commonly used crushing equipment. The grinding media is a ball or a cylindrical object in a ball mill. The grinding media of a common ball mill is mainly a metal ball and a cylinder. In the ceramic production industry, the ceramic grinding media is mainly used, followed by natural flint and pebbles. At present, China’s listed ceramic grinding media, including alumina grinding media, zirconia grinding media, silicon carbide bead, silicon nitride and other varieties. Alumina ceramic ball is an important engineering ceramics, is a high-tech products. Due to the appropriate hardness, moderate density, wear resistance, corrosion resistance, low price characteristics, and the introduction of metal ball metal impurities, so alumina ceramic ball is widely used in white cement, minerals, ceramics, electronic materials, magnetic materials , As well as paint, paint and other industries of raw materials, grinding and processing, is a high-quality grinding media [1, 2]. In the building ceramics industry, the alumina ceramic ball wear efficiency than natural flint and pebbles increased by 20% to 40% [3]. With the reduction of high quality natural ball stone resources, ordinary ceramic ball wear rate is high, alumina ceramic ball will be more and more ceramic manufacturers to use.

1 factors that affect wear resistance

The wear mechanism of alumina ceramics is divided into brittle fracture wear and plastic deformation wear. The wear characteristics of the former are the grain loss of intergranular fracture. The latter wear characteristics are micro-cutting of transgranular fracture, the former wear rate is larger than that of the latter Much more, people want the wear of the plastic for plastic deformation wear. The internal factors of ceramics have an important effect on the plastic deformation mechanism of ceramics. Alumina ceramic ball is a friction and wear components, the wear rate by the internal factors and external factors, which affect the internal factors. The wear resistance of alumina ceramics is closely related to the mechanical properties of the materials and the synergistic effect of the microstructures, ie, the internal factors (elastic modulus E, hardness H, fracture toughness K1c, grain size, grain boundary and Porosity), in recent years, people have done a lot of research [4 ~ 8]. Ceramic toughness and grain size is the most studied, and wear resistance of the most closely related internal factors, toughness of the ceramic friction and wear a great impact. As the smaller the grain, the better the wear resistance of ceramics, so wear-resistant ceramic is toward the direction of microcrystalline development. However, the cost of nano-alumina ceramics is very high, it is difficult to promote the use of engineering applications, so the alumina ceramic wear-resistant materials focus on several Lm grain size range has been a breakthrough and development.

  1. Production status quo

As of September 1999, China has nearly 30 alumina production enterprises, the production capacity of about 35 000 t / a, but the actual production capacity of about 18 000 ~ 20 000 t / a, a considerable number of enterprises in recent years has been low-volume operation , Far less than the design of the production capacity [9]. The scale of relatively large, more investment, advanced equipment, a high degree of automation companies in Shanghai Morgan Meichao (UK Morgan sole proprietorship, investment 120 million yuan), Henan Zhengzhou, Mengda and WuLong, Shandong Zibo HuaMing, Jiangsu Jiangdu SanShan, are used isostatic pressing, the annual output of about 1 000 T better quality alumina grinding media. As well as Guangdong Nanhai Nanzhuang (4 000 t / a), clever, Foshan, more than 20 use of radial pressure or even hand-molding,

Low quality level. At present, the common characteristics of domestic products is high wear rate, sintering temperature above 1580 ℃, sintering cycle more than 8 h. And most manufacturers of products due to dregs, cracking, broken and other issues become slow-moving products, more than half of manufacturers on the brink of collapse. Therefore, the need to solve the problem of high quality and high cost as soon as possible

3 improve the wear resistance

3. 1 A-Al2O3 raw materials

3. 1. 1 particles of the morphology of the ceramic is pressed by the high temperature from the firing made. The green body is made of granules, so the sintering of the ceramic is not only the sintering behavior between the particles, but also the sintering behavior of the green body. Sintering is an important part of ceramic firing. The factors that affect the sintering of the green body are quite numerous, and the intrinsic factors are the characteristics of the powder. Powder characteristics are one of the important factors affecting sintering. Surface energy is one of the driving forces of particle sintering, the morphology of the surface of the particles can have a great impact, so the particle morphology of the ceramic sintering effect is quite large [10]. Surface roughness of the particles, the specific surface area or surface energy is relatively large, so the sintering drive force, easy to sinter, sintered density, small holes and less. Smooth granular particles, the particle surface area or surface energy is relatively small, so the sintering driving force is small, not easy to sinter, ceramic sintering density is relatively low, large and large holes. Compared with granular particles, the plate-like particles have large specific surface area, large sintering driving force and easy sintering, and the sintered density of ceramics is larger. Compared with the small hard aggregates and non-aggregates, the porosity is high, the density of the green body is small, the density of the ceramic is small, and the sintered density of the ceramic is low.

3. 1.2 Size of the particles When the grain is relatively small, the wear mechanism is mainly plastic deformation and partial transgranular fracture, resulting in a slight wear; grain is relatively large, the wear mechanism is mainly grain boundary fracture, resulting in serious wear and tear The Therefore, the smaller the grain, the better the wear resistance of the ceramic. Therefore, as far as possible the use of small particle size A-Al2O3 raw materials in order to reduce the ceramic grain size. In addition, the small particles compared with the large particles, the specific surface area or surface energy is relatively large, so the sintering driving force, sintering temperature is low, while the sintering density is higher.

3. 2 combustion agent Suitable sintering agent to reduce the sintering temperature, improve the microstructure of ceramics, improve mechanical properties, thereby improving the wear resistance of ceramic balls. The quality of the sintering agent includes quantity, phase composition, chemical composition and fineness. Sintering agent generally use SiO2-CaO-MgO ternary system for formulation. Should try to avoid the use of high temperature gas release and phase change of the combustion agent, so as to avoid new defects, and affect the product of the densification and pass rate, reduce product competitiveness.

3. 3 forming the use of isostatic pressing technology to overcome the other molding methods hollow, layered, low density and uneven density and other defects. The particle size, shape and additives of the raw material all affect isostatic pressing. The molding pressure and packing time affect the density of the green body, sintering shrinkage rate, sintering temperature. Therefore, to use the appropriate raw materials and scientific molding process to ensure that the green has a good sintering characteristics.

3. 4 sintering system is too high sintering temperature and too long holding time will promote the growth of Al2O3 crystal, liquid phase increased, so not only the strength decreased, wear resistance will be weakened. Of course, the temperature is too low, the sintering density is reduced, the wear resistance of the porcelain ball decreases. If the sintering temperature is not appropriate, even if the Al2O3 content is high, the wear resistance is not necessarily good, the key depends on the phase composition and microstructure of the ceramic ball. The use of low-temperature fast burning technology, can be significant energy efficiency, while inhibiting the alumina ceramic ball grain growth, is conducive to improving product strength, toughness, thereby enhancing the wear resistance of ceramic balls. Boiling agent greatly affect the low temperature fast burning, the general use of SiO2 – CaO-MgO ternary system formula.

3. 5 Research Progress Researchers have made significant studies on the use of appropriate additives to reduce sintering temperatures and improve abrasion resistance, and have made significant progress [11-18]. Addition of 18% ~ 20% Y-PSZ in A-Al2O3 with an average of 1 ~ 1.5 Lm was carried out at 1 650 ℃ for 1 h. The relative sintering density was 98.8% and the wear rate was only 95 Porcelain ball 1/5 ~ 1/8 [13]. For 95 ceramic balls, when the weight of 0. 3% MgO, the best wear resistance, microstructure grain fine and uniform, the smallest pores [14]. A-Al2O3 conversion rate of the appropriate powder is extremely important, the conversion rate of high and low impact on the quality of alumina ceramic ball [11]. If the conversion rate of A-Al2O3 is high, its calcination temperature is relatively high, the hardness of the material increases the difficulty of grinding the powder, and the sintering activity is small, if the sintering temperature is increased, the grain growth will not only increase the cost Conducive to the formation of a uniform microstructure, abrasion resistance but decreased. If the conversion rate of A-Al2O3 is low, its calcination temperature is relatively low, the hardness of the material is weakened, grinding is relatively easy, sintering activity is large, but because of the crystal transition products produce greater shrinkage, resulting in porcelain ball cracking.

wear-resistant alumina grinding ball production and application

The current market sales of 75% Al2O3 ceramic ball, 80% to 95% Al2O3 ceramic ball, high alumina ceramic ball is more expensive, most of the current focus on some of the larger, high grade products, Chinese and foreign enterprises and large enterprises, And many small and medium enterprises dare not ask, thus limiting its promotion and application. In response to this problem, some people use our rich bauxite resources to develop wear-resistant ceramic ball, the product performance is not lower than the proportion of alumina powder as raw materials made of ceramic ball, and the cost is only the same level of gravity Of the alumina ceramic ball 50% to 70%, the price reduction of 20% to 40% [19 ~ 21]. 4 application

The bricks and glazes are used in the construction of the sanitary ceramics industry. The glazes are ground with a ball mill. Until now, most companies still use natural ball as a grinding medium, natural ball of stone due to poor wear resistance, grinding process will inevitably pollute the glaze, and because of the natural ball of small density, grinding efficiency is low. Seeking and using cheap and cheap grinding is one of the pursuit of ceramic enterprises. Since the 1950s, Al2O3 ceramic ball has entered the field of ceramic production. In 1998, China’s total output of building ceramics was 1.5094 × 109 m2, and the total output of sanitary ceramics was 51.55 million [22], accounting for 1/3 and 1/5 of the world’s output respectively. It was considered as the world’s largest building health Ceramic production countries, and from now until 2010, China is expected to have been to maintain the construction of sanitary ceramics world’s first production power status. According to the ideal product structure, high-grade products by 20% estimate, the national required alumina ceramic ball filling capacity of about 40 000 t, high-grade ceramic ball comprehensive demand should be about 50 000 t / a. With the natural gem on the verge of exhaustion, the current ideal of the ball has been difficult to buy, the quality of the ball with a high degree of serious impact on the quality of grinding materials, affecting the grade of products, forcing enterprises to choose excellent characteristics of alumina ceramic ball The The use of alumina ceramic ball for grinding media to improve product quality, ceramic industry is the consensus. Therefore, the alumina ceramic ball in the ceramic industry market demand is great. 5 Summary

Alumina ceramic ball with the appropriate hardness, moderate density, wear resistance, corrosion resistance, low price characteristics, is an important engineering ceramics, is a high-tech products. Alumina ceramic balls are widely used in construction sanitary ceramics, electronic materials, metallurgy, minerals, glass, cement, chemicals, paints, coatings and other industries, so the market is huge. From the raw material morphology, particle size, combustion agent, molding, sintering and other aspects of detailed research to further reduce the cost of alumina ceramic ball to improve its wear resistance. The use of China’s abundant bauxite mineral resources to develop wear-resistant ceramic ball to meet the needs of many small and medium enterprises. It is hoped that the wear of porcelain balls will change from brittle fracture wear to plastic deformation wear. It is of great theoretical and practical value to study the plastic deformation mechanism of porcelain ball.

Ball mill is widely used in metallurgy, mineral, power, building materials, chemical and other fields, is the most commonly used crushing equipment. The grinding medium is a ball or a cylindrical object in a ball mill. The grinding medium of a common ball mill is mainly a metal ball and a cylinder. In the ceramic production industry, the ceramic grinding medium is mainly used, followed by natural flint and pebbles. At present, China’s listed ceramic grinding media, including alumina, zirconia, silicon carbide, silicon nitride and other varieties. Alumina ceramic ball is an important engineering ceramics, is a high-tech products. Due to the appropriate hardness, moderate density, wear resistance, corrosion resistance, low price characteristics, and the introduction of metal ball metal impurities, so alumina ceramic ball is widely used in white cement, minerals, ceramics, electronic materials, magnetic materials , As well as paint, paint and other industries of raw materials, grinding and processing, is a high-quality grinding media [1, 2]. In the building ceramics industry, the alumina ceramic ball wear efficiency than natural flint and pebbles increased by 20% to 40% [3]. With the reduction of high quality natural ball stone resources, ordinary ceramic ball wear rate is high, alumina ceramic ball will be more and more ceramic manufacturers to use.

1 factors that affect wear resistance

The wear mechanism of alumina ceramics is divided into brittle fracture wear and plastic deformation wear. The wear characteristics of the former are the grain loss of intergranular fracture. The latter wear characteristics are micro-cutting of transgranular fracture, the former wear rate is larger than that of the latter Much more, people want the wear of the plastic for plastic deformation wear. The internal factors of ceramics have an important effect on the plastic deformation mechanism of ceramics. Alumina ceramic ball is a friction and wear components, the wear rate by the internal factors and external factors, which affect the internal factors. The wear resistance of alumina ceramics is closely related to the mechanical properties of the materials and the synergistic effect of the microstructures, ie, the internal factors (elastic modulus E, hardness H, fracture toughness K1c, grain size, grain boundary and Porosity), in recent years, people have done a lot of research [4 ~ 8]. Ceramic toughness and grain size is the most studied, and wear resistance of the most closely related internal factors, toughness of the ceramic friction and wear a great impact. As the smaller the grain, the better the wear resistance of ceramics, so wear-resistant ceramic is toward the direction of microcrystalline development. However, the cost of nano-alumina ceramics is very high, it is difficult to promote the use of engineering applications, so the alumina ceramic wear-resistant materials focus on several Lm grain size range has been a breakthrough and development.

  1. Production status quo

As of September 1999, China has nearly 30 alumina production enterprises, the production capacity of about 35 000 t / a, but the actual production capacity of about 18 000 ~ 20 000 t / a, a considerable number of enterprises in recent years has been low-volume operation , Far less than the design of the production capacity [9]. The scale of relatively large, more investment, advanced equipment, a high degree of automation companies in Shanghai Morgan Meichao (UK Morgan sole proprietorship, investment 120 million yuan), Henan Zhengzhou, Mengda and WuLong, Shandong Zibo HuaMing, Jiangsu Jiangdu SanShan, are used isostatic pressing, the annual output of about 1 000 T better quality alumina grinding media. As well as Guangdong Nanhai Nanzhuang (4 000 t / a), clever, Foshan, more than 20 use of radial pressure or even hand-molding,

Low quality level. At present, the common characteristics of domestic products is high wear rate, sintering temperature above 1580 ℃, sintering cycle more than 8 h. And most manufacturers of products due to dregs, cracking, broken and other issues become slow-moving products, more than half of manufacturers on the brink of collapse. Therefore, the need to solve the problem of high quality and high cost as soon as possible

3 improve the wear resistance

3. 1 A-Al2O3 raw materials

3. 1. 1 particles of the morphology of the ceramic is pressed by the high temperature from the firing made. The green body is made of granules, so the sintering of the ceramic is not only the sintering behavior between the particles, but also the sintering behavior of the green body. Sintering is an important part of ceramic firing. The factors that affect the sintering of the green body are quite numerous, and the intrinsic factors are the characteristics of the powder. Powder characteristics are one of the important factors affecting sintering. Surface energy is one of the driving forces of particle sintering, the morphology of the surface of the particles can have a great impact, so the particle morphology of the ceramic sintering effect is quite large [10]. Surface roughness of the particles, the specific surface area or surface energy is relatively large, so the sintering drive force, easy to sinter, sintered density, small holes and less. Smooth granular particles, the particle surface area or surface energy is relatively small, so the sintering driving force is small, not easy to sinter, ceramic sintering density is relatively low, large and large holes. Compared with granular particles, the plate-like particles have large specific surface area, large sintering driving force and easy sintering, and the sintered density of ceramics is larger. Compared with the small hard aggregates and non-aggregates, the porosity is high, the density of the green body is small, the density of the ceramic is small, and the sintered density of the ceramic is low.

3. 1.2 Size of the particles When the grain is relatively small, the wear mechanism is mainly plastic deformation and partial transgranular fracture, resulting in a slight wear; grain is relatively large, the wear mechanism is mainly grain boundary fracture, resulting in serious wear and tear The Therefore, the smaller the grain, the better the wear resistance of the ceramic. Therefore, as far as possible the use of small particle size A-Al2O3 raw materials in order to reduce the ceramic grain size. In addition, the small particles compared with the large particles, the specific surface area or surface energy is relatively large, so the sintering driving force, sintering temperature is low, while the sintering density is higher.

3. 2 combustion agent Suitable sintering agent to reduce the sintering temperature, improve the microstructure of ceramics, improve mechanical properties, thereby improving the wear resistance of ceramic balls. The quality of the sintering agent includes quantity, phase composition, chemical composition and fineness. Sintering agent generally use SiO2-CaO-MgO ternary system for formulation. Should try to avoid the use of high temperature gas release and phase change of the combustion agent, so as to avoid new defects, and affect the product of the densification and pass rate, reduce product competitiveness.

3. 3 forming the use of isostatic pressing technology to overcome the other molding methods hollow, layered, low density and uneven density and other defects. The particle size, shape and additives of the raw material all affect isostatic pressing. The molding pressure and packing time affect the density of the green body, sintering shrinkage rate, sintering temperature. Therefore, to use the appropriate raw materials and scientific molding process to ensure that the green has a good sintering characteristics.

3. 4 sintering system is too high sintering temperature and too long holding time will promote the growth of Al2O3 crystal, liquid phase increased, so not only the strength decreased, wear resistance will be weakened. Of course, the temperature is too low, the sintering density is reduced, the wear resistance of the porcelain ball decreases. If the sintering temperature is not appropriate, even if the Al2O3 content is high, the wear resistance is not necessarily good, the key depends on the phase composition and microstructure of the ceramic ball. The use of low-temperature fast burning technology, can be significant energy efficiency, while inhibiting the alumina ceramic ball grain growth, is conducive to improving product strength, toughness, thereby enhancing the wear resistance of ceramic balls. Boiling agent greatly affect the low temperature fast burning, the general use of SiO2 – CaO-MgO ternary system formula.

3. 5 Research Progress Researchers have made significant studies on the use of appropriate additives to reduce sintering temperatures and improve abrasion resistance, and have made significant progress [11-18]. Addition of 18% ~ 20% Y-PSZ in A-Al2O3 with an average of 1 ~ 1.5 Lm was carried out at 1 650 ℃ for 1 h. The relative sintering density was 98.8% and the wear rate was only 95 Porcelain ball 1/5 ~ 1/8 [13]. For 95 ceramic balls, when the weight of 0. 3% MgO, the best wear resistance, microstructure grain fine and uniform, the smallest pores [14]. A-Al2O3 conversion rate of the appropriate powder is extremely important, the conversion rate of high and low impact on the quality of alumina ceramic ball [11]. If the conversion rate of A-Al2O3 is high, its calcination temperature is relatively high, the hardness of the material increases the difficulty of grinding the powder, and the sintering activity is small, if the sintering temperature is increased, the grain growth will not only increase the cost Conducive to the formation of a uniform microstructure, abrasion resistance but decreased. If the conversion rate of A-Al2O3 is low, its calcination temperature is relatively low, the hardness of the material is weakened, grinding is relatively easy, sintering activity is large, but because of the crystal transition products produce greater shrinkage, resulting in porcelain ball cracking.

13 No. 23 No. 3 Qin Linqing, etc.: wear-resistant alumina grinding ball production and application

The current market sales of 75% Al2O3 ceramic ball, 80% to 95% Al2O3 ceramic ball, high alumina ceramic ball is more expensive, most of the current focus on some of the larger, high grade products, Chinese and foreign enterprises and large enterprises, And many small and medium enterprises dare not ask, thus limiting its promotion and application. In response to this problem, some people use our rich bauxite resources to develop wear-resistant ceramic ball, the product performance is not lower than the proportion of alumina powder as raw materials made of ceramic ball, and the cost is only the same level of gravity Of the alumina ceramic ball 50% to 70%, the price reduction of 20% to 40% [19 ~ 21]. 4 application

The bricks and glazes are used in the construction of the sanitary ceramics industry. The glazes are ground with a ball mill. Until now, most companies still use natural ball as a grinding medium, natural ball of stone due to poor wear resistance, grinding process will inevitably pollute the glaze, and because of the natural ball of small density, grinding efficiency is low. Seeking and using cheap and cheap grinding is one of the pursuit of ceramic enterprises. Since the 1950s, Al2O3 ceramic ball has entered the field of ceramic production. In 1998, China’s total output of building ceramics was 1.5094 × 109 m2, and the total output of sanitary ceramics was 51.55 million [22], accounting for 1/3 and 1/5 of the world’s output respectively. It was considered as the world’s largest building health Ceramic production countries, and from now until 2010, China is expected to have been to maintain the construction of sanitary ceramics world’s first production power status. According to the ideal product structure, high-grade products by 20% estimate, the national required alumina ceramic ball filling capacity of about 40 000 t, high-grade ceramic ball comprehensive demand should be about 50 000 t / a. With the natural gem on the verge of exhaustion, the current ideal of the ball has been difficult to buy, the quality of the ball with a high degree of serious impact on the quality of grinding materials, affecting the grade of products, forcing enterprises to choose excellent characteristics of alumina ceramic ball The The use of alumina ceramic ball for grinding media to improve product quality, ceramic industry is the consensus. Therefore, the alumina ceramic ball in the ceramic industry market demand is great. 5 Summary

Alumina ceramic ball with the appropriate hardness, moderate density, wear resistance, corrosion resistance, low price characteristics, is an important engineering ceramics, is a high-tech products. Alumina ceramic balls are widely used in construction sanitary ceramics, electronic materials, metallurgy, minerals, glass, cement, chemicals, paints, coatings and other industries, so the market is huge. From the raw material morphology, particle size, combustion agent, molding, sintering and other aspects of detailed research to further reduce the cost of alumina ceramic ball to improve its wear resistance. The use of China’s abundant bauxite mineral resources to develop wear-resistant ceramic ball to meet the needs of many small and medium enterprises. It is hoped that the wear of porcelain balls will change from brittle fracture wear to plastic deformation wear. It is of great theoretical and practical value to study the plastic deformation mechanism of porcelain ball.

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Post time: Jan-14-2020
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