In-situ investigation of the oxidation behavior of powdered TiN, Ti(C,N) and TiC coatings grown by chemical vapor deposition

SURFACE & COATINGS TECHNOLOGY

卷:406

Article

Kainz, Christina¹  Schalk, Nina¹  Saringer, Christian¹  Czettl, Christoph² 

[1] Univ Leoben, Christian Doppler Lab Adv Coated Cutting Tools, Dept Mat Sci, Franz Josef Str 18, A-8700 Leoben, Austria

[2] Ceratizit Austria GmbH, Metallwerk Plansee Str 71, A-6600 Reutte, Austria

关键词: Hard coatings;    Chemical vapor deposition;    Oxidation;    X-ray diffraction;    Ti(C,N);   

DOI  :  10.1016/j.surfcoat.2020.126633

来源: Elsevier

【 摘 要 】

Since hard coatings used in metal cutting applications are exposed to temperatures up to 1000 degrees C, their oxidation stability is a crucial parameter for the tool lifetime. Thus, within this work, the detailed oxidation mechanisms of chemical vapor deposited TiN, Ti(C,N) and TiC coatings were studied. Coating powders were subjected to a heat treatment between 420 and 940 degrees C in ambient atmosphere and their phase composition was monitored in-situ by X-ray diffraction. Rietveld refinement allowed to quantify the phase fractions of TiN, Ti(C,N), TiC, TiO2 rutile and TiO2 anatase at every measurement temperature. Combining this method with differential scanning calorimetry and thermo-gravimetric analysis allowed to precisely track the progress of the involved reactions during oxidation. TiN exhibits the highest oxidation onset temperature of 640 degrees C. This fact is attributed to the higher Gibbs free energy of the oxidation reaction compared to TiC and the large domain size of the nitride. The latter observation also explains the single-step reaction to rutile without anatase formation. In case of Ti(C,N) and TiC, rutile and anatase form in the course of the oxidation. Ternary Ti(C,N) displays the highest oxidation end temperature and is only entirely consumed at 880 degrees C. Owing to the lower Gibbs free energy of the oxidation and the lower domain size in comparison to the nitride, TiC exhibits the lowest oxidation onset and end temperature.

【 授权许可】

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