1, Unlike metals, the wear process of polymer materials basically does not involve material oxidation and electrochemical corrosion in the friction process, so the mechanism is relatively simple, but it is still challenging to solve the wear resistance of polymer materials with great physical differences.
2, From soft and elastic rubber to POM with stiffness similar to metal, from ink coating with 2um thickness to PEEK for making large valves, solid lubricants represented by micronized wax and PTFE play an important role in these fields.
As we know, the wear of non-metallic materials is mainly adhesive wear and abrasive wear. Adhesive wear is the transfer of material from one surface to another at the point of contact due to solid-phase welding during relative motion.
Abrasive wear refers to surface abrasion or loss of surface material caused by microprotrusions on hard particles or harder materials.
In the field of engineering plastics, due to the generally poor thermal conductivity of polymer materials, the local heat generated during the friction process is relatively easy to reach the melting or softening point of engineering plastics, when the friction between the solids becomes and the resistance of the molten polymer to the solids on the opposite side of the friction sub, resulting in greater adhesive wear, which often appears as fish scale under the electron microscope.
With the addition of micronized PTFE or layer lubricant such as molybdenum disulfide, the friction force and friction heat will be reduced due to the reduction of friction coefficient, and the adhesive wear is controlled. When the amount of PTFE micronized powder added is relatively large, the transfer film between the friction surface becomes smoother, reflecting better wear resistance, and the wear mode at this time is mainly the abrasive wear formed by the solid on the polymer opposite to the friction substrate, which often appears as a plough furrow under the electron microscope.
For engineering plastics filled with glass fiber, the glass fiber will be crushed on the friction surface to form new abrasive grains, and the technical index of glass fiber and the amount of filling will have a greater impact on the wear resistance of engineering plastics.
The working conditions of wear-resistant engineering plastics are very important factors, such as temperature, load, friction speed, dry and wet conditions. Take PA6 as an example, the coefficient of friction is maximum at medium load, and the coefficient of friction is maximum at about 150 degrees.
At present, the domestic modified wear-resistant engineering plastics, mostly add molybdenum disulfide, its wear-resistant mechanism is to rely on its lamellar crystalline structure, can only produce black or gray products, and in the presence of water conditions, molybdenum disulfide due to water lubrication will be greatly reduced. The use of PTFE (polytetrafluoroethylene) micro powder can solve such problems.
PTFE micro powder has a low molecular weight, the average molecular particle size can be as fine as 1.5 microns, the appearance of white powder, with high molecular weight PTFE resin has all the excellent performance, its outstanding features are: particles into a spherical, between the particles do not bond non-caking, excellent dispersion, small particle size and uniform, large specific surface area, low bulk density, high oil absorption value, dispersion in the solvent low viscosity, can It can be evenly mixed with other powder and liquid materials.
The use of PTFE micro powder can enhance the performance of the main material, such as
1）Abrasion resistance, friction resistance and scratch resistance
2) Easy decontamination properties
3) Anti-adhesive properties
4) Lubricity properties (for engineering plastics modification)
5) Anti-friction, anti-wear properties
Micronized powder can improve some properties of the main materials (i.e. engineering plastics, general plastics, coatings, inks, lubricants, films, rubbers and lubricants), and even small amounts added can produce results. This is because these micronized powders are resistant to harsh processing conditions and their properties remain virtually unchanged after they are incorporated into the host resin.
The addition of a certain percentage of micronized PTFE powder can provide
Self-lubricating wear resistance
Higher mold release properties
Faster processing speeds
For plastics, higher levels are needed when low friction, PV and wear resistance are required. The processing conditions for PTFE filled blends are the same as for the main material (e.g. plastic, rubber, etc.).
Nanjing Tianshi produces a variety of specifications of PTFE micronized powder, which can be adapted to different kinds of wear-resistant engineering plastic systems, from low temperature POM to very high temperature PEEK have relevant application cases, and also equipped with plastic wear test machine, high magnification microscope and other equipment, can assist customers to analyze the various problems encountered in the wear process.
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