Bearing bush with magnetron sputtering self-lubricating composite coating and production method thereof

Abstract

The invention relates to a bearing bush with a magnetron-sputtering self-lubricating composite coating layer and a production method for the bearing bush. A bearing bush is one of strength-bearing parts which are the most prone to failure and the most important in an engine. Double-layer bearings have a common problem of low fatigue strength, and three-layer bearings have a common problem of bad wear resistance. The bearing bush provided by the invention comprises a steel back layer, a bearing alloy layer, a nickel barrier layer and an antifriction coating layer which are successively disposed. The antifriction coating layer is made of an aluminum / stannum / carbon composite material. The composite coating layer comprises following elements by weight: 11.5-19.5% of Sn, 3.0-6.0% of C, 0.75-1.25% of Cu, and the balance being Al. According to the invention, the bearing bush coating layer produced through a magnetron-sputtering self-lubricating composite coating manner has good compactness; nearly all materials can obtain a thin film through the magnetron-sputtering self-lubricating composite coating manner; and the coating layer is free from toxic elements such as lead, etc., and therefore the bearing bush provided by the invention has a good environmental protection performance.

Description

technical field [0001] The invention belongs to the technical field of sliding bearings of internal combustion engines, and in particular relates to a bearing bush with a magnetron sputtering self-lubricating composite coating and a production method thereof. Background technique [0002] The bearing bush is the most prone to failure in the engine, and it is also one of the most important load-bearing parts. With the development of the automobile industry, people have higher and higher requirements on the power and speed of the engine, so the service conditions of wear-resistant parts such as bearing bushes and bushings are further deteriorated, and the performance requirements are becoming more and more stringent. When the bearing pad is in service, when the engine is working, the bearing pad needs to bear a load of up to 700MPa, which is much higher than the yield limit (100~300MPa) of the alloy lining and steel backing, which will easily lead to the loss of the elastic te...

AI Technical Summary

Problems solved by technology

At present, the domestic engine bearings are mainly imported from Miba Company in Austria, and the Japanese bearing strips are also electroplated with binary and ternary coatings. The coated bearings have insufficient fatigue performance, especially poor anti-seizure performance.

The 59 Research Institute has conducted research on textured bearing bushes for high-power engines to improve the mosaicability of the coating. However, due to the use of electroplating to coat the coating, the bonding of the coating is poor, the coating is easy to contain inclusions, and the fatigue strength is binary. Plating has improved, but still only reaches 45MPa, which is far behind the fatigue strength of 50~70MPa abroad

The centrifugal casting three-layer bearing bush of the 466 factory adopts the centrifugal casting method, the bonding force of the alloy layer is poor, the structure segregation is serious, and defects such as slag inclusions, cracks, pores, and looseness are easy to occur, so the performance is unstable and it is difficult to apply it to high-speed engines.

[0015] Vacuum sputtering AlSn20 coating, which belongs to the type of alloy coating with soft particles distributed on the hard substrate. The hard substrate protrudes during operation, reducing the contact area between the shaft and the bearing bush, thereby protecting the normal operation of the shaft. The soft spots are sunken by wear and stored for lubrication. However, on the one hand, the AlSn20 coating has a coarse columnar crystal structure. With the development of high-speed engines, the bearing load limit is required to be much higher than 400N / mm 2 , fatigue strength > 75MPa, can no longer meet the requirements of use, and is prone to cracks and failures. Therefore, it is necessary to explore the preparation process, prepare equiaxed crystal coatings, and use the mutual coordination of multi-grain deformation, and a large number of internal grain boundaries can improve deformation on the one hand. On the other hand, the friction coefficient of AlSn20 metal coating is relatively high, which is about 0.4. In use, a liquid lubricant must be used to ensure the normal operation of the bearing bush. However, there are many problems in the use of lubricants. :

[0017] Under some harsh working conditions, for example, with the improvement of the assembly accuracy level between mechanical components, it is difficult for the lubricating fluid to form a continuous lubricating film in the assembly gap of the components and lose the lubricating effect; During the friction, the temperature of the contact surface is very high, and the lubricating effect of the lubricating fluid at high temperature will be greatly reduced;

[0018] (2) Environmental pollution Lubricating waste liquid used will cause serious environmental pollution

[0020] (3) Increased cost

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