Wear-resistant and low-friction coatings and articles coated therewith

Abstract

A composition for a wear-resistant and low-friction coating is presented. The coating composition includes a hard ceramic phase, a metallic binder phase and a lubricant phase. The lubricant phase includes a multi-component oxide. An article having a wear-resistant and low-friction coating and a method of making such a coating are also described.

Description

BACKGROUND[0001]This invention generally relates to coatings for articles. Particularly, the invention relates to protective coatings, which provide wear resistance and low-friction characteristics to articles exposed to high temperatures. Examples of such articles include turbomachines, such as turbine engines.[0002]Metal components are used in a wide variety of industrial applications, under a variety of operating conditions. In many cases, the components are provided with coatings, which impart various characteristics, such as corrosion resistance, heat resistance, oxidation resistance, and wear resistance. As one example, the various components of turbine engines are often coated with thermal barrier coatings, to effectively increase the temperature at which they can operate. Other examples of articles that require some sort of protective coating include pistons used in internal combustion engines and other types of machine.[0003]Wear-resistant coatings (often referred to as “we...

AI Technical Summary

Benefits of technology

[0012]Another embodiment is an article. The article includes a metallic substrate and a wear-resistant and low-friction coating disposed on the substrate. The coating composition includes a hard ceramic phase, a metallic binder phase and a lubricant phase, wherein the lubricant phase includes a multi-component oxide.

Problems solved by technology

The coatings provide protection in areas where components may rub against each other, since the rubbing—especially high frequency rubbing—can damage the part.

Fretting can often result from very small movements or vibrations at the junction between mating components, e.g., in the compressor and / or fan section of gas turbine engines.

This type of wear can necessitate premature repair or replacement of one or more of the affected components.

Various alloys, such as those based on nickel or cobalt, are susceptible to fretting and other modes of wear.

Many titanium alloys have especially poor fretting characteristics.

While hard chromium coatings have been of great use in various applications, they exhibit some drawbacks.

For example, the integrity of these coatings is challenged by the high temperatures and pressures to which they are often subjected, in both aerospace and automotive engine applications.

Furthermore, chromium plating can be a very time-consuming process.

Moreover, the toxicity of some of the chromate compounds used as the chromium source is another drawback to the plating processes.

The special handling procedures can often result in increased costs and decreased productivity.

While the resulting coatings are suitable for many purposes, they have limitations as well, e.g., in their thermal properties.

While many of the cermet coatings are suitable for certain end uses, they also exhibit deficiencies.

For example, the hardness of the WC— and Cr3C2-based coatings may be insufficient for other end uses, as mentioned above.

Moreover, WC—Co coatings are usually restricted to temperatures below about 500 degrees Celsius, in oxidizing environments.

This limitation is often seen in a thermal spray process such as HVOF or APS, and is due in part to carbide degradation during deposition.

Carbide degradation can occur when a WC material is oxidized, and forms brittle sub-carbides.

However, they may not have adequate low-friction properties and, moreover, it is difficult to control the microstructure of such coatings during thermal spraying.

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