What are the most commonly used wear-resistant materials?
Iron: The surface is chrome-plated and wear-resistant and smooth
Steel: Hardened and ground, wear-resistant and smooth
Carbide: After grinding, wear-resistant and smooth
Other materials: copper, graphite, engineering plastics, ceramics
Advantages and disadvantages of different wear-resistant materials
Metallic material:
Advantages: high strength, high hardness, high temperature resistance;
The disadvantage is: the coefficient of friction is large
Engineering Plastics:
Advantages: small friction coefficient, high wear resistance;
The disadvantages are: medium and low strength, medium and low hardness, and high temperature resistance of 100-300 degrees.
Composite:
The performance is between metal materials and engineering plastics.
Ceramic material:
It has the properties of metal materials, high temperature resistance, much lower density than metal, and relatively large friction coefficient.
What is wear-resistant ceramics?
Wear-resistant ceramics are ceramics with excellent wear resistance. Currently, alumina ceramics, zirconia ceramics, zirconia donated alumina (ZTA) and silicon carbide ceramics are widely used. Among them, alumina ceramics are the most cost-effective.
Which ceramic is the most wear-resistant?
Silicon nitride ceramics are the most wear-resistant, and silicon nitride, with the molecular formula Si3N4, is an important structural ceramic material. It is a superhard substance, which has lubricity and wear resistance; strong corrosion ability and oxidation resistance at high temperature.
From the current technical ability, zirconia ceramics are the most wear-resistant, because of its good toughness and high hardness, the only disadvantage is that the price is too high.
Is Zirconia Toughened Alumina (ZTA) a ceramic?
Zirconia Toughened Alumina (ZTA) is an inorganic non-metallic material and is a good wear-resistant ceramic material.
ZTA is the addition of pure zirconia to alumina. When zirconia is added appropriately, the toughness of alumina ceramics can be significantly improved. Usually, the addition ratio of zirconia exceeds 20% to achieve the toughening effect.
Which is more wear-resistant, ZTA or alumina ceramics?
In actual use, ZTA is more wear-resistant than alumina ceramics
Alumina ceramic material has excellent properties such as high temperature resistance, high strength, creep resistance, wear resistance, good insulation, and light weight. It is an ideal structural ceramic material and has been widely used in many industrial sectors.
With the development of science and technology, the application field of alumina ceramics has been continuously expanded. As a new type of structural ceramic material, it has been used in new technologies such as parts of high-power generators, precision machined parts, and parts in the field of electronic technology. field.
The application in these new technological fields puts forward higher requirements for the properties of alumina ceramic materials.
Due to the brittleness of alumina ceramic materials, its application range is limited. In order to overcome the brittleness of alumina ceramic materials and improve safety and reliability, it is necessary to toughen them. The more mature and widely used toughening method is ZrO2 toughened.
The Mohs hardness of alumina ceramics is 9, and the Mohs hardness of zirconia ceramics is 8.5. However, from the perspective of industrial wear-resistant ceramics, the higher the hardness, the better. It also depends on the toughness, hardness and toughness of the ceramics. Must be high, can be said to be the best wear-resistant ceramics.
At room temperature, the hardness of alumina ceramics is higher than that of zirconia ceramics, and theoretically, the wear resistance is better.
ZTA toughened alumina ceramics add certain zirconia ceramic ingredients on the basis of alumina. The wear resistance and toughness are between alumina ceramics and zirconia ceramics, and the comprehensive wear resistance is better.
Alumina wear-resistant ceramic
Wear-resistant ceramics are special ceramic materials made of calcined alumina powder (AL2O3) as the main raw material, rare metal oxides as additives, and sintered at a high temperature of 1500 ° C. They can be used alone or with special rubber and high-strength organic materials. /Inorganic binder to form other composite wear-resistant products.
Performance characteristics of alumina wear-resistant ceramics
High hardness:
Its Rockwell hardness is HRA80-90, second only to diamond in hardness, far exceeding wear-resistant steel and stainless steel;
Excellent abrasion resistance:
The wear resistance is equivalent to 266 times that of manganese steel and 171.5 times that of high-chromium cast iron. Under the same working conditions, the service life of the equipment can be extended by more than ten times.
Lightweight:
The density is 3.6-3.9g/cm3, which is only half of that of steel, which can greatly reduce the equipment load.
Several technical data of alumina wear-resistant ceramics:
Water absorption:
The ratio of the mass of water absorbed by all open pores in a dry material with pores to the mass of the dry material, expressed in %.
Density:
The ratio of the mass of the dry material with pores to its total volume, expressed in g/cm3 or kg/m3.
Bending strength at room temperature:
Under normal temperature, when a load is applied at a specified pressing speed, the maximum load that the product can bear per unit area before failure is expressed in Mp.
Compressive strength at room temperature:
At room temperature, the maximum stress that a cuboid specimen of specified size can withstand on a three-point bending device, expressed in Mp.
Moh’s hardness:
A measure of mineral hardness. The surface of the mineral is scratched by using the scratch method to carve the surface of the mineral with a pyramid-shaped diamond needle. It is customary to use the Mohs hardness in mineralogy or gemology. The hardness is expressed in ten grades by the depth of the measured scratches.
Vickers hardness:
Use a load within 120kg and a diamond square cone indenter with an apex angle of 136° to press into the surface of the material, and divide the surface area of the material indentation pit by the load value, which is the Vickers hardness value (HV).
Maximum service temperature of alumina wear-resistant ceramics
The alumina wear-resistant ceramic itself is sintered at a high temperature of 1500 degrees Celsius and can operate at 1000 degrees Celsius.
Although the alumina wear-resistant ceramic itself can withstand high temperature, the adhesive or rubber combined with the working surface has a temperature limit, and it is generally recommended that the maximum use temperature should not exceed 200 °C. If it is to be used at a higher temperature, it is recommended to use Wear-resistant ceramics that engage each other.
How to choose the right wear-resistant ceramic sheet
When choosing wear-resistant ceramics, the first thing to consider is the conveying method of materials, that is, air conveying or conveying materials by belt or natural drop.
Generally speaking, the equipment of the air conveying system is seriously worn, but the impact is not large, and wear-resistant ceramics with high hardness should be selected.
For other material handling systems, the toughness (impact resistance) of wear-resistant ceramics should be the first concern, followed by the hardness of the ceramics. Thickening the ceramic and improving the fracture toughness of the ceramic by improving the formula can greatly improve the impact resistance of the wear-resistant ceramic.
In addition, the working conditions of wear-resistant ceramics, such as the location of the specific working surface, working temperature, etc., should be comprehensively considered.
Common installation methods for wear-resistant ceramics
There are three commonly used installation methods for wear-resistant ceramic sheets:
Bonding, welding and dovetail occlusion, among which welding is divided into ordinary welding and stud welding.
Wear-resistant ceramic sheet glue construction
It is recommended to use a high temperature resistant inorganic adhesive (adhesive for wear-resistant ceramics), which has excellent adhesion, processability and thixotropy to both steel and ceramics; it can be cured at room temperature; it has quite high strength and toughness; has high heat resistance and aging resistance.
Wear-resistant ceramic sheets are usually made of modified epoxy resin, usually A and B components. This kind of glue is based on epoxy resin glue with other modified ingredients to improve its strength, impact resistance and weather resistance, but this kind of glue is generally more expensive. For large-scale construction, you can also use ordinary Epoxy resin glue, although the strength of epoxy resin glue is not as good as the modified one, its strength is also sufficient, and the main cost-effectiveness is higher.
Precautions for construction of wear-resistant ceramic glue
Before the wear-resistant ceramic tiles is pasted to the surface of the steel part, the surface of the steel part should preferably be pretreated by sandblasting to remove rust and keep the surface smooth, and then wipe the surface of the steel part with acetone to achieve a certain degree of degreasing.
The proportion of wear-resistant ceramic adhesives should be strictly controlled, and the adhesives with inappropriate proportions cannot achieve the predetermined bonding strength;
The wear-resistant ceramic adhesive should be applied evenly, and the wear-resistant ceramic is easy to fall off where there is no adhesive or too little adhesive is applied. After the wear-resistant ceramic sheet is pasted and constructed, it should be gently tapped with a rubber hammer to make the construction surface smooth;
The wear-resistant ceramic tiles must be clear about the working temperature before construction. The wear-resistant ceramic patch can withstand a high temperature of 1000 ° C, which is much higher than the temperature resistance of the adhesive. Different working temperatures should choose glue with different temperature resistance, otherwise The wear-resistant ceramic sheet will fall off as the working temperature increases.
Construction method of wear-resistant ceramic sheet glue
The normal temperature wear-resistant ceramic sheet adhesive is used to paste wear-resistant ceramic sheets on the working surface under 120 ℃ that is eroded by ash powder and the working surface that is strongly eroded or eroded by materials. It is suitable for thermal power, steel, smelting, machinery, coal, mining, industries such as ports and agriculture.
Instructions
Surface Treatment
Grind or sandblast to remove dust, oil and rust on the surface of steel parts, and finally clean with cleaning agent.
Formulated Adhesives
Mix the two components uniformly according to A:B (mass ratio)=1:2.
Apply Adhesive
Apply the adjusted adhesive evenly to the surface of the steel part to be pasted with ceramics.
Cured
It can be completely cured after 24 hours at room temperature or heated to 80°C after 2 hours at room temperature, and kept for 4 hours until it is completely cured.
Amount of Wear-Resistant Ceramic Epoxy Adhesive
The construction amount of wear-resistant ceramic adhesive depends on the thickness (weight) of the ceramic. If it is a relatively thin ceramic, 1.6 kg/㎡ is enough. If the ceramic is very thick, the dosage can be increased to 2 kg/㎡.
What industries can alumina wear-resistant ceramics be used in?
The industries where alumina wear-resistant ceramics are widely used are metallurgy, thermal power, coal washing plants, cement plants, mines, granaries, docks and other industries that have a large number of material transportation requirements.
Features of composite wear-resistant pipes
The composite wear-resistant pipe gives full play to the advantages of high strength, good toughness, impact resistance, good welding performance and high hardness, high wear resistance, corrosion resistance and heat resistance of the wear-resistant ceramic lining of the steel pipe. Disadvantages of poor abrasiveness and poor ceramic toughness. Therefore, the composite pipe has good comprehensive properties such as wear resistance, heat resistance, corrosion resistance, mechanical and thermal shock resistance, and good weldability. It is widely used in thermal power, metallurgy, mining, coal, chemical industry, port, agriculture and other industries. wear resistant pipes.
Wear-resistant ceramics for steel mill chute liners
The high-temperature impact-resistant wear-resistant ceramic lining of the steel mill chute can replace the manganese steel lining to fundamentally solve the wear problem of these equipment.
The high-temperature impact-resistant wear-resistant ceramic lining plate is made by welding the toughened ultra-thick wear-resistant ceramics to the inner wall of the equipment by stud welding to form a solid impact-resistant and wear-resistant layer. For easy installation and replacement, the wear-resistant ceramics can be pre-installed on the steel plate, and then installed on the inner wall of the equipment by welding or countersunk head bolts.
Which industries can ceramic wear-resistant pipes be used for
Ceramic wear-resistant pipes are widely used, and currently have the following applications:
Power plant boiler powder conveying pipeline, coarse and fine powder separator pipeline, coal falling pipeline, primary air pipeline, secondary air pipeline, tertiary air pipeline and burner pipeline, slag discharge pipeline, powder return pipeline, dry ash pipeline;
Steel plant raw material conveying pipeline, receiving pipeline, dust removal pipeline, ash discharge pipeline, ash falling pipeline, batching mixing pipeline, grinding outlet pipeline, coal burning pipeline, coal powder pipeline, separator pipeline, burner square and round pipe, etc.;
Cement plant separator outlet pipeline, separator inlet pipeline, dust collection pipeline, vertical mill air outlet duct, circulating air duct, coal mill high temperature fan air duct, blanking pipe, etc.;
Various pipe fittings for processing and conveying materials in petroleum, chemical, mining, coal, coal washing plants, smelting, papermaking, aluminum industry, building materials, powder engineering, grain machinery, etc.
What are the wear-resistant materials for fan impellers?
Wear-resistant ceramic fan impeller refers to pasting alumina ceramic sheets at the outlet of the fan impeller and the connection between the blade and the rear disc to improve the wear resistance. On the basis of the traditional fan manufacturing technology, the wear-resistant ceramic lining is pasted on the main working surface of the fan equipment to form a surface layer with excellent wear resistance, which can increase the service life of the fan impeller by more than three times and increase the fan efficiency by 10-30 %.
The wear-resistant ceramic fan impeller is suitable for thermal power plants, powder dischargers, thermal plants, coking plants, cement plants, steel mills, blast furnace fans, sintering fans, circulating fans and other conditions that convey hard particles and corrosive media.
The service life of the wear-resistant ceramic fan impeller is related to the size, concentration, speed and scouring angle of the dust particles. The smaller the particle, the lower the concentration, the lower the scouring speed and the smaller the scouring angle, the longer the service life of the wear-resistant fan impeller.
Rubber-backed-ceramic plate (3 in 1 ceramic rubber composite plate) applications
Thermal power, steel, cement industry, port, smelting industry, chemical industry, coal industry, mining industry, silicone industry, etc.
Composite Wear Elbow with Wear Ceramic Liner
The composite wear-resistant elbow is made of alumina wear-resistant ceramics pasted on the inner wall of the metal elbow, and the alumina content is not less than 92%. Alumina ceramics have high melting point, high hardness, and excellent wear resistance. The hardness of alumina ceramics is second only to diamond, and the surface smooth friction coefficient is small, and the wear resistance is very ideal, especially in high temperature oxidizing media or corrosive media, the performance of ceramic materials is much better than other metal materials, from the actual use effect From the point of view, it can effectively prolong the service life of the elbow.
Service life of alumina wear-resistant ceramics
There is no mandatory warranty period for alumina wear-resistant ceramics. Some industries have a one-year warranty period, and there are other periods specified by each user. The length of the warranty period is restricted by factors such as operating conditions, product quality and construction level. , the replacement cycle needs to comprehensively consider factors such as the thickness of the ceramic paste, operating pressure, temperature and wear severity.
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