1. There are various silicon carbide ceramics, which type suits me best? You can select the type according to the characteristics of the above materials, your actual working conditions, cost and other factors. Take commonly seen clean water pump as an example, from the perspective of cost, reaction-sintered silicon carbide should be selected; from the perspective of long service life and high reliability, pressureless sintered or graphite-containing silicon carbide can be considered while the cost is higher; if there is possible impact or vibration in the working condition, liquid-phase sintered silicon carbide should be selected; for corrosive medium conditions hot-pressing sintered, pressureless sintered or graphite-containing silicon carbide; even if
for corrosive medium conditions, if

2. How to use the easiest methods to distinguish the quality of silicon carbide ceramic?
(1) Check the color Usually the performance of silicon carbide ceramic relates to its purity, higher purity reflects higher hardness and better corrosion resistance. High-purity silicon carbide ceramic such as single crystal of silicon carbide ceramic is light yellow. With the increasing impurities, the color gradually deepens. Depending on the types and content of impurity, the color gradually becomes light green, green, light gray, dark gray, gray-black and black. Usually the darker color means the more impurities contained. High-purity alumina is transparent. Checking the color can roughly determine the purity.|
(2) Observe the fracture Crack a workpiece or observe the fracture of broken workpieces to judge the quality. Fractures of good ceramic should be fine and smooth, shiny, and uniform colored with delicate uniform state like cheese. Fractures of inferior ceramic are rough and uneven with different grain sizes, tiny air holes, and dark and not bright color. (3) Measure the density This method is simple and reliable. Common ceramic has different materials as well as densities; therefore the comparison between the actual measured density and theoretical density of the material can help with the determination of the quality of such material. The material with closer density to theoretical density has better quality. The measurement of the density is simple as long as there is a scale. Measurement methods can quote national standards. There is a certain correspondence between the actual density of common ceramic materials and other properties, as long as the actual density can meet the

requirements and its color and fracture are normal, the performance of that ceramic material can be basically guaranteed.
(4) Measure the hardness Enterprises with good conditions can measure the hardness of ceramic pieces as a basis for final decision. Most of ceramic pieces are used in wear-resistant, corrosion-resistant or high-temperature-resistant conditions, and observe the purity from color and material quality from fracture and density, the above three factors can basically help with the judgment of application for corrosion and heat resistance while for wear resistance hardness measurement is also needed. Wear resistance and hardness of the material is directly proportional, and higher hardness means better wear resistance. In practical work, many users judge the quality of parts by striking them, this method is very unscientific and very unreliable. For the plastic material, such as metal materials, such method can have certain reliability, while ceramic is a brittle material with many factors affecting the results of striking, and such results are extremely unreliable. For example, use a sharp corner of ceramic parts to hit the surface of marble slab, the corner of the ceramic pieces is seriously broken while the marble slab has just a groove mark, which helps to conclude that the hardness of marble slab is better than that of silicon carbide ceramic pieces, such conclusion is seriously wrong. Of course, the most reliable method is a comprehensive test of various properties of the ceramic, but this requires a lot of money and long time. Ceramic manufacturers must do this, but common users can not afford it.

3. Is it important to judge the type of silicon carbide ceramic?
Yes, very. Various silicon carbide ceramic materials have greatly different performances and great impact on service life of the parts in the actual use. To some extent, this is the basic guarantee of long-term, stable and reliable operation of products. If you use the workpiece in corrosive media for long while you

choose liquid-phase sintered or reaction-sintered silicon carbide, the reliability can be imagined.
Different materials are suitable for different working conditions, and in actual work the difference between maintenance costs and reliabilities is obvious. Each customer wants to obtain the greatest benefits at the lowest cost, and thus the cost you pay should obtain the benefit you need.

4. Dos and Don'ts during application process of ceramic parts
As ceramic parts are brittle materials, attention should be paid to the following matters in the process of installation and use:
(1) Handle with care during the installation process, avoid knocking, press with slow force increase.
(2) A small amount of lubricating oil, grease, or tap water can be brushed at intervals or during the installation of transition fit parts with slow and gradual pressure for complete installation in place. Alignment and parallel between the centers of axle and hole must be ensured during installation process, if the gap is too small, exit timely and check whether the size meets the requirements. Never force to install in order to prevent damages of the ceramic pieces' chipping, cracks or breaks.
(3) Interference fit assembly must be installed in the form of hot charging. The heating temperature can be calculated according to the size and coefficient of thermal expansion of the material of the two mating pieces. Ceramic material is brittle material with low tensile strength but high compressive strength, and generally it should not be used as the kit for withstanding tensile stress but the chipware for compressive stress.
(4) Ceramic material is brittle with poor loading capacity for striking, therefore after installation, use manually-operated turning gear to

check the changes in the moving resistance and dynamic balance.
If the moving resistance is strong and manually-operated turning gear can possibly feel the resistance change, detach the assembled parts and recheck their size, gaps, geometric tolerance etc and reinstall after confirmation. Ensure the smooth, light, and resistance-free operation of manually-operated turning gear. After confirming no problem can the gear be operated, but remember to accelerate gradually. If vibration can be felt during acceleration, stop and check the dynamic equilibrium state to eliminate the vibration source. Remember that ceramic part can never work under the conditions with vibration, otherwise there will be very serious consequences ranging from sharp decrease of service life of ceramic parts to broken ceramic pieces that cause major safety accident.
(5) After operation, observing the temperature rise of the ceramic parts. Generally if the design and installation have no problem, the temperature will not rise soon, and during long-time work the maximum temperature is not very high. Usually the temperature rise in ten minutes cannot reach 50 degrees, and the maximum operating temperature for long time (the highest temperature that no longer rises after over one-hour operation) should not be over 90 degrees. Of course, ceramic parts specifically for high temperature are excluded.

5. Storage of ceramic parts
Ceramic parts are brittle, and for storage there should be proper packaging to avoid collisions between parts. Handle with care in porting process, and avoid vibration during transport to prevent damage.
Ceramic parts are made of inert material with good chemical stability,

non-radioactivity, no environmental pollution, and excellent corrosion resistance, therefore exposure to moisture, rain, sunshine and steam has no effect on its performance. Meanwhile, they have stable performance and no problem of service period or deterioration, and storage time has no effect on the performance