Just Joined Viadeo

Join Viadeo, the professional social network chosen by John Yeatman and more than 35 million professionals

I’m told it’s much bigger in some parts of the world than LinkedIn, so best give it a try I suppose!

Tantalum

TaCl5 Generator

Tantalum is an extraordinary metal. It has a melting point of 3017degC which makes it the third highest metal behind Tungsten and Rhenium. This is a useful property, however it is its extreme chemical resistance that makes it most interesting. Below 150degC it is inert to aqua regia (mixture of concentrated hydrochloric and nitric acids). Aqua regia dissolves other metals, such as gold and platinum,  normally thought of as inert, in a trice.

Tantalum has a variety of uses, the biggest of which is in capacitors, but for coatings, the interest in mainly in putting an extremely corrosion resistant layer onto fasteners, crucibles, pipe bores etc.  In the last year the price of tantalum metal has rocketed and this is expected to stimulate interest in coatings where solid tantalum components could be replaced by cheaper metals coated with tantalum.

Tantalum is fairly easy to deposit by CVD, normally from TaCl5 & hydrogen. The main difficulty is that TaCl5 is practically impossible to evaporate in a controlled manner. TaCl5 melts at 216degC and evaporates at around 240degC  The change from liquid to vapour involves dissociation of the dimer Ta2Cl10 to the monomer, so this complicates things. It is also hygroscopic so that any exposure to air completely  changes the evaporation properties. ATL overcomes this problem by generating the tantalum in situ through the reaction of chlorine gas with tantalum metal. Obviously handling a gas as toxic as chlorine is not to be taken lightly, but it does make Ta CVD a reliable, repeatable and scalable process. Chlorine is cheap and tantalum scrap is relatively easy to buy, although prices are currently eye-watering (I blame the Chinese).

ATL has developed and sell its own design of industrial scale TaCl5 generator. Transport of up to 1Kg per hour of Ta metal is possible with the current design. These are available for sale either as part of a complete turn-key coating system or as a bolt on to customers’ existing CVD equipment. Control can be stand alone or incorporated into the main system. The same generators can be used for making TaC coatings which are of increasing interest in the semi-conductor market.

Silicon Carbide

Silicon Carbide deposited by CVD is a wonderfully versatile material with a myriad of applications and excellent physical properties.

Its high hardness means it has abrasive and protective applications.

Its 100% dense structure combined with excellent chemical resistance gives it corrosion resistance applications.

Its high temperature strength combined with low density (3.2 g/cc) makes it an ideal space, rocketry and aerospace material.

These properties plus its low neutron activation cross-section makes it an ideal material for fission and fusion applications.

All those tiles on the underside, leading wing edges and nose cone of the Space Shuttle may have got bad press, but they are SiC and there’s no better material.

All silicon chips have passed across CVD SiC Coated furniture during their manufacture. The SiC is dense, pure and inert enough to keep the required  incredibly high purity levels. For the most critical semiconductor applications, the furniture is made from solid CVD SiC. This is possible because SiC is one of those materials (like tungsten) that can be deposited several cm thick by CVD.

I could go on an on, but then I really would be rambling!

So you want to know about ATL?

ATL Presentation
So now you know all about CVD: It’s the process for you and you are looking for a CVD specialist. Look no further!
Make sure you’ve got your sound switched on.
Apologies for the blatant self-publicity, but it is a pretty nifty presentation.

So you want to know more about CVD?

CVD Presentation

A rather nifty presentation on CVD, how it works, its applications and advantages.

Make sure you’ve got your sound turned on!