1 Introduction
Rolling the rings , rolling elements and cage components. As the rings and rolling contact points by the applied load and rotation effects , which repeatedly generates contact pressure and deformation. Due to the characteristics of the material properties of steel bearing itself , mainly in the form of bearing failure is fatigue spalling , short fatigue life, a very limited range of applications . The ceramic material (Si3N4) has a low density , medium elastic modulus, thermal expansion coefficient, high hardness , high temperature , corrosion-resistant , non-magnetic , etc., silicon nitride ceramic balls as the rolling element bearing ceramic ball bearings can significantly improve contact fatigue life , greatly expanding the application fields of rolling bearings , has been widely used in various high-precision , high- speed machine tools, automobiles , car , subway , motors , aircraft engines , petrochemical machinery, metallurgical machinery and other fields. Currently , silicon nitride ceramic balls and ceramic ball bearings have started to enter the mass production stage , particularly in the field of application of corrosion -resistant machine bearings prospects with high-speed precision spindle bearings and high temperature .
2 silicon nitride ceramic material properties
2.1 Low Density
Due to the low material density ceramic rolling elements , centrifugal load is small, which can operate at higher speeds , and generate less heat.
Elastic modulus 2.2 Medium
Elastic modulus of the ceramic rolling element rolling the steel is high, the dynamic stiffness of the bearing is improved, but the elastic modulus of the stress concentration is reduced too much the light carrying capacity of the bearing .
2.3 Thermal expansion coefficient
Help to reduce the thermal expansion coefficient of the sensitivity to temperature changes , thereby preventing jamming . Mixed roller bearings , wider operating speed range applicable .
2.4 high compressive strength
Rolling high compressive strength is needed to withstand the high contact stresses ( the ceramic material , its strength is usually broken by three-point or four-point bending test as measured modulus decision ) .
High hardness and high toughness 2.5
These two features combine good surface roughness can be obtained , but also to prevent damage to the hard particles and the external impact .
2.6 Good resistance to rolling contact fatigue properties
This performance requirements for the bearing rolling elements is essential.
2.7 spalling failure mode
If rolling fail at work, it should be fatigue spalling , the practical form of death in the card portentously , is a practical form of minimal harm . In some applications the higher application conditions ceramic material also has some special properties.
2.8 High temperature and stability
In the high temperature environment up to 800 ℃ stably maintain its mechanical properties.
2.9 corrosion
Oxidizing and corrosive environments , especially in repeated rolling and squeezing out the surface film should have a contact area of ​​oxidation and corrosion stability .
Although the silicon nitride ceramic materials in industry is not the hardest , toughness is not the highest , but in bearing applications that require high performance , silicon nitride is considered to have the best integrated mechanical and physical properties. Comprehensive testing and rolling contact bearings peel tests have proved dense and homogeneous silicon nitride material has good resistance to rolling contact fatigue properties. Industrial silicon nitride ceramic bearing steel material and performance comparison is shown in Table 1.

Table 1 Performance comparison of industrial ceramics and bearing steel

3 domestic ceramic ball bearings Market Analysis and Outlook
3.1 Domestic Market
3.1.1 Ceramic Ball Bearings for Machine Tools
Machine with ceramic ball bearings are used in a variety of machine tool spindle and ball screw .
Refers to general machine tool spindle bearings , feed system , transmission bearings, various high-speed high-power electric spindle bearings , grinding grinding bearings and a variety of CNC machine tools , machining centers and automatic processing lines needed bearings. Such high precision bearings , precision of P2, P4, P5 level . This kind of bearing high technology content, high added value , stable performance, long life and difficult process . Conventional steel bearings can not fully meet the high speed and high precision machine tool requirements , and the ceramic ball bearings can be a good remedy this .
( 1 ) CNC machine tools with ceramic ball bearings
CNC machine tools including CNC lathes, machining centers, CNC grinding , EDM , CNC machine tools , such as forging , machine tools such angular contact ceramic ball bearings are generally used dmon ≥ 80X104 precision, the high-speed spindle. " 15" end CNC machine tool production in the country will reach 30,000 to 35,000 units, of which 10,000 units of CNC lathes , machining centers, 3,000 units , 1,500 units of CNC grinders , EDM 10,000 units , 600 units of CNC metal forming machine , CNC heavy machine 100 Taiwan, with an average of each CNC machine tool spindle bearings and install four sets of precision ceramic ball bearing calculation , the precision bearings and ceramic ball bearings annual demand of 140,000 units. Among them, ceramic ball bearings annual demand of 40,000 units.
( 2 ) grinding machine spindle with ceramic ball bearings
Grinding spindle surface grinding machine is mainly used for high-speed , high precision and speed requirements. " 15" end , the national high-frequency spindle with precision bearings and ceramic ball bearings annual demand will reach 350,000 units, of which , ceramic ball bearings at 50% of total demand , the annual demand for ceramic ball bearings 17.5 million units.
( 3 ) Other metal processing machine tool spindle bearings with ceramic balls
Expects 2005 annual production capacity of metalworking machine tools 200 000 -22 million units, bearing the total demand of 16.5 million -1775 million units , after deducting the inner surface grinding machine CNC machine tools and other metal processing machine is about 18 million units, with each metalworking machine tools installed a set of average precision bearings and ceramic ball bearing calculation , the precision bearings and ceramic ball bearings annual demand of 180,000 units, of which , ceramic ball bearings annual demand of 50,000 units.
( 4 ) Machine Ball bearings with ceramic balls
Ball used to transfer linear motion with high precision and high axial rigidity, low torque and remarkable features long life , widely used in precision mechanical equipment , precision measuring tools CNC machine tools indispensable accessory .
Ceramic ball bearings with a precision ball screw and ball screw installation rigidity is an important factor to ensure high precision and high axial stiffness . Ball bearing structure at home and abroad is usually used in high-precision angular contact ball bearings, these bearings are very strict , required to achieve the international standard ISO P4 level and above , in order to improve the axial bearing capacity , usually using a large contact angle of 600 bearings. To achieve a great axial rigidity , the most common is the use of a group installation.
With the expansion of production scale CNC machine tools and CNC machine tools increased social ownership society also will be increased demand for ball screws . According to the development of the machine tool industry forecasts , China's demand for the Ball 1995 120 000 , 2000 was 160,000 , is expected to 2005 was 200,000 , each supporting precision ball screw bearings Vice average by four sets of calculations, 2005 precision ball screw bearings domestic demand of 80 million units , according to 20 percent with ceramic ball bearings , the ceramic ball bearings annual demand of 16 million units.
Therefore , CNC machine tool spindle , grinding spindle, and other metalworking machine spindle bearings and precision ball screws require a total of 1.47 million sets of ceramic ball bearings , of which 425,000 sets of ceramic ball bearings .
Machine tool industry is the basis of the equipment industry , is a measure of the overall economic strength of the country flag . According to the machine tool industry, "15 " planning objectives, metal processing machine tools in 2000, annual production will increase to 160,000 units in 2005, 200,000 -22 million units, including CNC machine tools will be 20,000 units in 2000 to 30,000 to 3.5 million units ( according to the actual situation of production and sales in recent years , the production and sales of CNC machine tool industry will exceed planning ) , accounting for 15% of total production , domestic machine tool market share of 60% -65 % ; industrial output value of 2000 200 billion yuan to 23 billion in 2005 to 250 billion yuan. The analysis calculation predicts that in 2005 supporting the bearing metal processing machines totaling 7.5 million -825 million units, of which about 1.5 million of CNC machine tools supporting the bearing sleeve ; 2005 metalworking machine maintenance with bearing demand 9,000,000 -950 million units, of which NC machine maintenance bearings around 1.8 million units. Thus , in 2005 metalworking machine tool precision bearings and ceramic ball bearings total demand 16,500,000 -1,775 million units , of which about 3.3 million of CNC machine tools demand sets . Thus, the domestic machine tool industry with ceramic ball bearings market prospects .
3.1.2 Chemical Machinery with ceramic ball bearings
Chemical Machinery ceramic ball bearings are mainly used for a variety of industrial pumps supporting bearings , including oil transfer pumps, electric submersible pumps , injection pumps, booster pumps , centrifugal pumps, centrifugal pumps, corrosion resistant pumps, reciprocating pumps, vortex pumps, screw pumps, crude oil refining pumps, deep processing of pumps, chemical process pumps , wear pumps and hydraulic pumps , etc., demand is expected to yield a variety of pumps in 2005 will reach 18 million units, each pump an average two sets of precision bearings and ceramic calculation ball bearings, bearing demand in 2005 to 36 million units , of which 90,000 sets of ceramic ball bearings .
In summary, the 2005 domestic chemical industry, machine tools and precision bearings and ceramic bearings totaling 1.81 million units, of which , 515,000 sets of ceramic ball bearings .
At present , the domestic Luoyang Bearing Science & Technology Co., Ltd. ceramic balls and ceramic ball bearing technology leading domestic level , with ceramic balls accuracy of G3 ~ G5 grade ceramic ball bearings to achieve mass production .
3.2 foreign markets
Ceramic ball bearing applications gradually expand the international market , the demand increases, there is a huge potential for development. Currently, the United States, Japan ceramic ball bearing technology in the world leading level.
Due to the advantages of silicon nitride ceramic material itself , silicon nitride ceramic ball bearings in high-temperature , high-speed , high-pressure , cryogenic , vacuum, strong corrosive , anti- magnetic , non-lubricated , under special circumstances , such as work wear , and steel bearings can not meet the requirements. Silicon nitride ceramic ball is now widely used in aviation engines, a variety of high-precision , high- speed machine tools, automobiles , car , subway , electrical , petrochemical machinery, metallurgical machinery and other fields. In 1984, Japan's Koyo Seiko (KOYO) in the world's first successful ceramic balls , ceramic ball bearings bulk sale as a commodity . As 6205 ceramic ball bearings in the Hong Kong market price of $ 110 ; U.S. NORTON successfully ceramic ball bearings in the pump on the space shuttle , due to the light weight of the bearing , the speed can be increased 0.5-1 times, and less or no lubrication oil ; Japan ceramic ball bearings in corrosion industry , aerospace engines, machine tools, metro and other areas have been widely used . Swedish SKF company to supply desalination NASA regulations ceramic bearing temperatures up to 800 ℃, service life 4-6 times higher than steel bearings ; SKF companies to set up offices in Shanghai, Beijing country , the operation of the company's silicon nitride ceramics bearings, ceramic bearings price of about $ 120 / set ; Japan NSK company currently has 28 kinds of specifications of three levels of angular contact ceramic ball bearings , which typically ceramic ball bearings, high-speed ceramic ball bearings, high speed and high load of ceramic ball bearings, such as : ROBUST low heat speed bearings , corrosion-resistant bearings , YS vacuum bearings , clean environment with a bearing , SJ high-temperature bearings, insulated bearings and trains with AC traction motors and ceramic rolling elements , machine tool spindle bearings, and lubrication technology innovation in product technology, product quality assurance and product sales, has formed a complete system. According to incomplete statistics , in 1996 before the World Ceramic bearings sales have more than 400 million U.S. dollars .
Our research started later than ceramic bearings in industrial countries for nearly 30 years, but research, application , testing the pace of China's rapid progress in ceramic ball bearings . To develop national machine tool industry , to improve the accuracy of machine tools to meet other special applications, ceramic bearings will play a key role in a decisive , and the use of new nano- composite ceramic materials is to improve precision ceramic bearing product trends and performance .