Any help will do. Any examples anything plz.. Your company is considering synthe

Question

Any help will do. Any examples anything plz..

Your company is considering synthesizing an alumina coating by depositing Al using a plasma sputtering technique onto an Fe-Si alloy and then oxidizing the coated alloy at 1000 degree C. In considering the advantages and disadvantages for the coating you are requested to explain the following issues to the company's small engineering group: What composition of the Fe-Si alloy must be used so as not to form a melt along the interface between the Fe-Si alloy and AI coating? For the Fe-Si alloy, which you selected, what phases will form along the Fe-Si/AI interface upon cooling to room temperature after the AI melts? Instead of depositing AI via plasma sputtering why not simply immerse the Fe-Si alloy into an AI melt contained by graphite, silicon carbide or alumina crucibles? Compare the possible concerns or advantages to the plasma AI sputtering and AI melt immersion, as well as the processing benefits of using a specific crucible, if any. In considering the above issues, discuss technically by using binary and ternary phase diagrams your reasoning for selecting the Fe-Si alloy, as well as calculating the AI-C-O stability diagram at 1000 degree C for explaining the ramifications of selecting the crucible. Would any advantages or disadvantages exist for forming a ternary intermetallic compound? How would you cause or retard the formation of the intermetallic?

Explanation / Answer

2.2 Sputtering Targets

Sputtering of metallic layers is straightforward. For the sputtering of dielectric

layers there are two different approaches. The first is to use ceramic target materials of the desired layer composition. The second is a reactive sputtering process,

where a metallic target is sputtered in a reactive atmosphere of oxygen or nitrogen.

Most sputtering processes for interference coatings use metallic target materials.

In reactive sputtering processes there is not only a reaction on the substrate but

also on the surface of the metallic sputter target. A stable sputtering process needs

optimised management of reactive gas and cathode power. Most processing problems (such as arcing) result from dielectric layers grown on the target surface.

Ceramic targets are seldom used because of two severe disadvantages. One disadvantage is that most of the ceramic materials are non-conductive and cannot be

operated using Direct Current (DC) power. To install RF (Radio Frequency)

power is expensive, it induces a low sputter rate and is complicated. The second

disadvantage is the high production cost of ceramic target materials.

Ceramic targets are only used where an extremely precise stoichiometry of the

dielectric layer is required . The best example is the production of ITO-layers with

In2O3/SnO2 targets. The use of conductive TiO2 targets is also increasing (Weigert

2001).

Materials for sputtering targets have to fulfil specific requirements: The most

important characteristics include:

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