Microstructure and properties of Ti(C,N) coatings produced by moderate temperature chemical vapour deposition

In this work, Ti(C,N) coatings produced by moderate temperature chemical vapour deposition (MTCVD) were investigated and compared with Ti(C,N) coatings produced by conventional CVD. Detailed characterisation of the microstructure was made using transmission electron microscopy in combination with electron diffraction and electron energy-loss spectroscopy. The mechanical properties of different Ti(C,N) coatings were also dealt with. The deposited Ti(C,N) coatings had a twinned columnar microstructure with strong [112] texture. Large {001} crystal faces result in a rough and facetted surface. MTCVD coated tools have higher transverse rupture strength values than CVD coated ones, due to reduced decarburisation of the cemented carbide substrates and lower residual tensile stresses. Reduced decarburisation and the absence of the reversible η-phase reaction lead to improved edge strength.