What are the types of cermet?

01
Oxide based cermet



(1) Al2O3-based cermet
Al2O3-based cermets Alumina Ceramic Tube can be used as cutting tools and are suitable for high-speed cutting. Al2O3-based cermets with Cr as the metal component have higher mechanical strength than Al2O3 ceramics, and with the increase of Cr content in the composition, the flexural and tensile strengths increase. Using Cr-Mo alloy is better and can be used in many high temperature conditions. For example, as jet flame controllers, bushings for missile nozzles, molten metal flow control needles, "T" gates, furnace tubes, flame protection rods, thermocouple protection sleeves and mechanical seal rings, etc. Al2O3-Fe-based cermets have high hardness, wear resistance, corrosion resistance, and high thermal stability, and are widely used as mechanical seal rings, as well as mechanical seals for agricultural submersible pumps. parts. The ring has a long service life and will not break the ring due to a large amount of heat generated by a temporary start.


(2) ZrO2-based cermet
ZrO2-based cermets are another type of ceramics Alumina Ceramic Ring that can be bonded with metals and can be made into useful refractories. ZrO2-based cermets bonded with 5% to 10% atomic concentration of Ti can be made into crucible materials suitable for making rare and active metals.


(3) Other oxide-based cermets
BeO-based cermet uses W as the bonding metal, which has good thermal shock resistance and softens at higher temperatures. This material is used to make crucibles. ThO2-based cermets with W or Mo as the bonding metal can be made into many products used in the electronic industry. Cermets composed of fissionable UO2 bonded by Al, stainless steel or W can be used as fuel elements in nuclear reactor cores. This cermet can better inhibit fission products and has good thermal conductivity, thereby preventing melting at high temperature.

02
Carbide based cermet



(1) WC-based cermet
WC-based cermets are the most studied and widely used cermets among carbide-based cermets. So far, the best classical example of structural combinations and interatomic interactions that can guarantee high mechanical properties of materials is still WC-Co-based cermets. Because the structural parameters of the phase components are similar at 20 °C, and the high-temperature transformation of Co is from a face-centered cubic lattice to a hexagonal lattice by the twinning method. This transition is initiated by the low energy of Co alignment defects, which generate strong dislocation splitting within Co, thus guaranteeing a high yield limit.


(2) TiC-based cermet
Among carbide-based cermets, in addition to WC, TiC-based cermets are also well studied and widely used. Since the melting point (3250°C) of TiC ceramics is higher than that of WC (2630°C), its wear resistance is good, its density is only 1/3 of that of WC, its oxidation resistance is much better than that of WC, and it can be wetted by Co, which can be used to replace the current WC-Co-based cermets, which are widely used in the cutting tool industry, have attracted great interest due to their greatly reduced cost.


(3) Cr3C2-based cermet
The cermet with Cr3C2 as the main component and Ni, Ni-Cr or Ni-W as the bonding metal has a series of excellent properties such as low density, wear resistance, good corrosion resistance, low thermal expansion coefficient and good high temperature oxidation resistance. performance, which Alumina Ceramic Parts has been used in tools and the chemical industry. It can be used as a guide ring for saltwater fishing rods, bearings and sealing materials for corrosion and wear resistance of hot saltwater, block gauges, micrometer joints and other measuring tools, brass extrusion dies, high temperature bearings, valve balls for oil well valves, etc.

03
Carbonitride based cermet


Ti(C,N)-based cermet is a new type of metal developed on the basis of TiC-based cermet with high hardness, high strength, excellent high temperature and wear resistance, good toughness, low density and high thermal conductivity. ceramics. Its main component is TiC-TiN, Co-Ni is used as binder, and other carbides are used as additives, such as WC, Mo2C, (Ta, Nb)C, Cr3C2, VC, etc.

At present, the application of Ti(C,N)-based cermets in the machining field has become a reality to make various micro indexable inserts for fine boring and fine hole machining, as well as "turning instead of grinding" and other finishing fields , and because Ti(C,N)-based cermet has low density, low friction coefficient, high wear resistance, good acid and alkali corrosion resistance and stable high temperature performance, it can also be used for: high temperature parts of various engines, such as Small bearing bush, impeller root flange, valve, valve seat, push rod, rocker arm, Ceramic Part eccentric shaft, hot nozzle and piston ring, etc.; can also be used for various sealing rings and valves in the petrochemical industry, and also suitable for various measuring tools, such as Slip gauge, plug gauge, ring gauge.

04
boride-based cermet



(1) TiB2-based cermet
Due to the unique physical and chemical properties of TiB2 ceramics, such as: extremely high temperature hardness, low density and resistivity, high elastic modulus, good thermal conductivity, low adhesion and friction coefficient with metals, high oxidation resistance, chemical It has good stability, etc., so it is considered to be a promising hard phase for the manufacture of a new generation of cermets.


(2) ZrB2-based cermet
ZrB2-based cermets with mass fraction of 0.02-0.05 B to bond ZrB2 can be used at extremely high temperatures, including reaction systems of combustion chambers, rocket engines and jet engines. With the reaction of SiC and ZrB2 with a mass fraction of 0.15, this consolidated cermet can further enhance the oxidation resistance of ZrB2, and can withstand the oxidative environment in the range of 1900-2500 °C. This cermet can be used in systems that handle molten metal, such as impellers and bearings for pumps used to die-cast liquid alloys on die-casting machines; nozzles Metallized Alumina Ceramic for atomizing metal powders; and furnace parts that come into contact with molten reactive metal or vapor.

05
Cermets containing graphite or diamond-like carbon


The graphite-metal composite materials for making electrical contacts can be used for: metal brushes for electric motors and motors, the metal phase of which is copper or bronze; sliding contacts at lower friction speeds and low contact pressure, the metal phase is silver. In addition, these materials are widely used to make brake linings and clutch linings. Grinding, polishing, sawing, cutting, dressing and reshaping tools are made by adding cermets ranging from coarse chips to fine powdered diamonds in a metal matrix.