Structural ceramics mainly refer to a large class of new ceramic materials that exert their mechanical, thermal, chemical and other properties. They can serve in many harsh working environments, and thus become the key to the realization of many emerging science and technology.
Cubic boron nitride is a superhard material that is only 20 to 40 percent harder than diamond. Although second only to diamond in hardness, CNB surpasses gemstones in other important areas: The composite material does not react to carbon, making it possible to process steel, which accounts for 90 percent of mechanical engineering materials. By contrast, diamond reacts with one of its constituents, carbon, limiting its usefulness. Instruments made from nano-CNBs can cut metals that were previously uncut.
Advanced ceramics, which are different from traditional ceramics in terms of raw materials and processes, usually use high-
purity, ultra-fine raw materials, and make ceramic materials with excellent performance through composition and structural design, accurate stoichiometry and new preparation technology
Chemical inertness, high wear resistance and thermal shock resistance at high temperature make silicon carbide a favorite for a variety of refractory applications. Typical examples include kiln furniture, aluminum reduction cell, incinerator, bricks for blast furnace and zinc furnace, crucible, integral parts, clay at tap hole and runner for furnace, etc.
How can a fragile material like ceramics be used to make watches?
Although the most common materials in the watch industry are stainless steel, titanium, precious metals (gold, platinum, rose gold, platinum), etc., one of them belongs to the rising star in the watch material industry - ceramic material, which has sprung up under the attack of the above-mentioned materials in recent years. More and more watch brands have launched their own ceramic watches. Ceramic has become a widely used material in the watch industry.
Recently, the scientific research team led by researcher Wang Shiwei of Shanghai Institute of silicate, Chinese Academy of Sciences, cooperated with Jiangxi zhongkete ceramic new materials Co., Ltd. to break through the key bottlenecks such as deformation and cracking of large-size ceramic blank during drying and sintering based on the spontaneous solidification molding system with independent intellectual property rights, The super large-size high-purity alumina ceramic disc with a diameter of 1010mm (Fig. 1) and the double-layer concentric high-purity alumina cylinder with an outer diameter of 200mm (Fig. 2) were successfully prepared. The main performance indexes of the material are better than those of similar foreign products.
Based on the traditional melt deposition method, dense and porous zirconia ceramics were prepared by 3D printing with particle mixture and screw extrusion mechanism. The printing properties of particle raw materials, microstructure characteristics of green body and mechanical properties of ceramic materials were systematically studied. The results show that this method can print the unsupported structure with an inclination of 165 ° and a span of 5.5 mm; The effects of two printing paths on the flexural strength and Weibull modulus of dense zirconia ceramics were studied. The results show that the "single line rectangular" composite filling mode can obtain ceramics with higher density and better mechanical properties than the traditional single line filling mode. The flexural strength is 637.8 MPa and the Weibull modulus is 9.1; The compressive mechanical behavior of porous zirconia ceramics with different porosity is studied. The results show that there is a composite index law between compressive strength and porosity. The stress-strain curve of out of plane compression only shows an elastic stage at low porosity, and there are elastic stage and collapse stage at high porosity, but there is no compaction stage.
Biomaterials introduced before are mainly used to repair and replace human bones with wounds, lesions or congenital defects, or repair materials that can be permanently implanted into the body. Recently, an absorbable bioceramic material has been developed rapidly. This material is a form of tricalcium phosphate called "synthos". This material is made into porous bone blocks and implanted into the damaged parts of the human body. When the adjacent tissues proliferate and grow in the implanted body, the tricalcium phosphate can be slowly replaced by the regenerated bone of animals. This process is called biodegradation process, so this kind of material is also called biodegradation material or bioabsorbent material.
1. Clinical application of bioactive glassThe most representative bioactive glass for clinical application is developed by Americans with a composition of (wt%) Na2O 24 5、CaO 24、SiO2 45、P2O56. 0 glass…
Since July 1, China's national phase VI motor vehicle pollutant emission standard for heavy diesel vehicles has been officially implemented throughout the country. It is prohibited to produce and sell heavy diesel vehicles that do not meet the national VI emission standard, and imported heavy diesel vehicles shall meet the national VI emission standard. It is reported that the national six emission standards have upgraded and improved the automobile exhaust test procedures compared with the national five, and the automobile exhaust pollutant emission limits have been stipulated. The severity has been increased by 40% ~ 50%, and the emission of main pollutants has been nearly doubled. From this point of view, the upgrading of automobile exhaust emission products is an essential work for major automobile enterprises.