Applications of polyurethane elastomers

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This post was last edited by ljtjbx on 2016-2-17 08:54. Wear refers to the phenomenon where the surface materials of two objects come into contact with each other and wear away due to friction. It is very necessary to research and develop wear-resistant materials suitable for different fields in order to reduce wear and extend the service life of equipment. The wear resistance of a material generally refers to its ability to resist wear under specific friction conditions. For example, various vibrating screens, magnetic separator drums, flotation machines, flotation tanks, mixing tanks, slag chutes, slurry pumps, belt conveyor drums, coal mine conveyor belts, and spiral mixers used in mining equipment are subject to severe wear caused by different types of slurries during operation, which affects their service life. By spraying a wear-resistant elastomeric coating of a specific thickness on the working surface of these devices, the impact and damage caused by irregular particles such as slag, ore, and coal cinders on the device surface can be significantly reduced, thereby extending the device’s service life. The wear behavior of spray-applied wear-resistant elastomers is extremely complex, especially under conditions of rolling contact between the surface and slurries containing irregular particles such as mortar; the wear of the elastomer coating involves almost simultaneously various types of wear, including fatigue wear, curling wear, abrasive wear, and even scraping wear. Different types of wear have given rise to corresponding wear testing methods, such as Akron wear, which is characterized by curling wear; DIN wear and NBS wear, which are dominated by abrasive wear; and Taber wear, which is associated with fatigue wear. The results of wear tests are generally expressed in terms of wear strength, which refers to the amount of wear per unit of time or per unit distance. The amount of wear can be expressed as volume wear or mass wear. Volume wear includes Akron wear and DIN wear; mass wear includes Taber wear. Additionally, the results of wear tests can also be expressed as a wear index, which is the ratio of the wear amount of the sample tested under identical conditions to the wear amount of a standard sample, such as NBS wear. Therefore, studying the test data on different levels of wear under laboratory conditions holds significant theoretical value in helping to improve the wear resistance of elastomeric coatings under actual friction conditions. There are now many types of wear-resistant materials available, but polyurethane elastomers excel at addressing various forms of wear, especially that occurring in slurry conditions, demonstrating their outstanding wear-resistant properties! Polyurethane elastomers can be sprayed and applied by hand. The development of elastic polyurethane spraying materials in China started relatively late, but there are still many products of this type that hold a leading position in the domestic market. This polyurethane elastomer possesses excellent overall properties, with a modulus that lies between that of ordinary rubbers and plastics. It possesses the following properties: ① High strength and elasticity, capable of maintaining high elasticity over a wide range of hardness levels (Shore A10–Shore D75) ； ②At the same hardness, it has a higher load-bearing capacity than other elastomers ； ③Excellent wear resistance; its wear resistance is 2-10 times that of natural rubber ； ④It has good fatigue resistance and vibration resistance, making it suitable for high-frequency flexure applications ； ⑤High impact resistance ； ⑥Aromatic polyurethanes exhibit excellent radiation resistance, oxygen resistance, and ozone resistance ； ⑦Excellent oil and chemical resistance ； ⑧The desired low hardness can generally be achieved without the need for plasticizers, thus avoiding problems associated with plasticizer migration ； ⑨The molding and processing costs are low. Under normal circumstances, compared to metal materials, polyurethane elastomer products have advantages such as light weight, resistance to wear and tear, low noise levels, low processing costs, and corrosion resistance ； Compared to rubber, polyurethane elastomers have advantages such as wear resistance, cut resistance, tear resistance, high load-bearing capacity, castability, potting capability, transparency or semitransparency, ozone resistance, and a range of hardness levels ； Compared to plastics, polyurethane elastomers have advantages such as resistance to brittleness, elastic memory, and wear resistance.