PVD/CVD Hybrid Coatings Craft IV: Project No. BE97 - 5318

Nowadays, coatings with good wear and corrosion resistance consist in high thickness Ni or hard Cr coatings from electrochemical processes. These technologies, well suited for some application, have two main drawbacks

1. They are poorly adapted in case of high mechanic stress due to hydrogen embrittlement
2. These wet processes lead to very polluting aqueous effluent. The pollution caused by these technologies is the major reason for replacing these techniques by non-polluting ones like vacuum technologies.

The economic weight of wear is equivalent to a market of 151 billion ECU in Europe per year. That is the reason why the wear resistance is the first quality that has to be satisfied by surface treatment.

Combining these two important facts, hard coatings from vacuum technologies has expanded significantly over the past several decades and are now commonly used in various industrial sectors like transport, tools and mechanics for their environmentally friendly characteristics and good wear resistance properties.

But their main problems lie upon the fact that in case of combined solicitation in wear and corrosion, these coatings are no more efficient. Such combinations are often encountered in various fields such as pumps, industrial equipment’s for food processing, domestic appliance, automotive, aeronautics where also additional effects (thermal cycling vibrations and mechanical fatigue) occur.

The two main vacuum technologies have this limitation that they are well suited for one kind of solicitation - physical vapour deposition (PVD) allows good wear resistance, and chemical vapour deposition (CVD) gives good corrosion resistance.

Thus the objectives of this project are

• to develop a non polluting coating technique combining Chemical and Physical Vapour Deposition
• to associate CVD material for corrosion resistance and PVD hard coating for wear resistance to obtain a multi-functional coatings able to satisfy combined aggression
• to develop a CVD based and PVD processes coupled in the same deposition facility for cost reduction