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Investigation of hard gradient PVD (Ti, Al, Si)N coating

Dobrzański L. A., Wosińska L., Mikuła J., Gołombek K., Gawarecki T.

Journal of Achievements in Materials and Manufacturing Engineering

2007

Vol. 24, nr 2

59-62

Purpose: Investigation of gradient coating of (Ti,Al,Si)N deposited on the Al203+SiC(w) oxide ceramics substrate by cathodic arc evaporation CAE-PVD method. Design/methodology/approach: Structure of substrate and coating was investigated with use of scanning electron microscopy (SEM). The X-Ray Photoelectron Spectrometry (XPS) examination was carried out for proving the gradient character of the (Ti,Al,Si)N coating. The investigation includes also microhardness and roughness tests of the deposited coating and used substrate; The Ra surface roughness parameter measurements were made on confocal microscope. Findings: Gradient structure and main properties of the investigated materials were introduced. It has been stated, that properties of the oxide tool ceramic with gradient (Ti,Al,Si)N coating increase in comparison with uncoated material. Practical implications: Depositing the wear resistant gradient coating onto the Al203+SiC(w) oxide tool ceramic results in a significant increase of the surface layer microhardness, contributing most probably in this way in machining to the decrease of the wear intensity of cutting tools' flanks made from the Al203+SiC(w) oxide tool ceramic. Originality/value: Functionally gradient coating form is a new class of structures in which the microstructure and properties vary gradually from the surface to the interior of the material.

Synthesis, characterization and mechanical properties of nanocrystalline NiAl.

Dollar M., Choudry M., Estman J.

Inżynieria Materiałowa

1998

R. XIX, nr 4

803-812

Nanocrystalline, ordered NiAl (n-NiAl) was successfully synthesized and compacted at various temperatures. The as-consolidated specimens exhibit grain sizes between 2 and 12 nm, a homogeneous chemical composition, and densities between 78 and 94% of the theoretical density, increasing with increasing compaction temperature. Microhardness of the n-NiAl increases with increasing grain size and density, above all as a result of reduced porosity following compaction at increasing temperatures. The present material is significantly stronger than its conventional countepart but not as strong as predicted by Hall-Petch-type modelling. Also, in the nanocrystalline form, NiAl exhibits room temperature ductility, unlike its coarsegrained countepart. The mechanical behaviour of n-NiAl can be rationalized assuming that diffusional - rather than location - mechanisms control strength and ductility of nanocrystalline materials.