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Posted by mark00 On April - 2 - 2010

The TiN coating has now been superceded in many machining applications by the TiAlN coating. The exact colour of the TiAlN coating is dependent on the Ti:Al ratio and can range from black to bronze.

TiAlN offers superior performance than TiN for a range of metal machining and fabrication applications. The is due to the addition of aluminium, which reacts with the oxygen in the atmosphere to form aluminium oxide on the surface. This increases the operational temperature range of the coating to 800 deg.C compared with 500 deg C for TiN.

This operating temperature has recently been increased by the addition of chromium and yttrium or vanadium to the coating increasing the temperature range to beyond 900 deg.C.

The high hot hardness and oxidation resistance (the aluminium oxide layer prevents further oxidation) properties of the TiAlN coating mean that it is used in high temperature cutting operations with minimum use of lubricant or dry machining. TiAlN is used quite successfully to machine titanium, aluminium and nickel alloys, stainless steels, alloy steels, Co-Cr-Mo and cast irons. TiAlN is also used to protect dies and moulds such as those in medium and hot forging and extrusion industries.