Oxidické nečistoty v Ti-Si-N a podobných systémech skrývají fázovou segregaci, tvorbu stabilních nanostruktur a degradují řezivost nástrojů povlakovaných nanokompozitními povlaky.

Oxygen Impurities in Ti-Si-N and Related Systems are Hindering the Phase Segregation, Formation of Stable Nanostructure and Degrading the Cutting Performance of Tools Coated with the Nanocomposites

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We have shown earlier, that an oxygen impurity content of more than0.4 at.p. (4000 ppm) strongly degrades the hardness of the nc-TiN/a-Si3N4 nanocomposites. Here we show that such impurities also hinder the phase segregation and formation of stable and strong nanostructure consisting of 3-4 nm size TiN nanocrystals "glued" together by about 1 monolayer thick interfacial Si3N4-like layer, thus apparently stabilizing the solid solution at high temperature of more 900C, as reported by other researchers. At the impurity content of only few hundred ppm, the segregation is completed, and a stable nanostructure formed at temperature less 550C. By decreasing the impurity content from 2000-3000 ppm down to about 1000 ppm in an industrial PVD coating equipment, the life time of cutting tools has been increased by a factor of 2.

Jak jsme již dříve prokázali, oxidické nečistoty obsahu více než 0.4 at.p (4000 ppm) silně degardují tvrdost nc-TiN/a-Si3N4 nanokompositů. V tétéo práci prokazujeme, že takovéto nečistoty mohou také skrývat fázovou segregaci stabilních TiN nanostrukturních krystalů velikosti 3-4 nm. Tyto TiN nanokrystaly jsou spojeny 1 monovrstvou Si3N4-, která zdánlivě stabilizuje tuhý roztok o tepotách vyšších 900C, jak uvádí i jiní autoři. O obsahu pouhých několika ppm se tvoří segregace stabilní již při mene 550C. Snížení obsahu nečistot z 2000-3000 ppm pod 1000 ppm má výrazný účinek na řezivost nástrojů, jejichž řezivost se porlouží minimálně dvojnásobně.

We have shown earlier, that an oxygen impurity content of more than0.4 at.p. (4000 ppm) strongly degrades the hardness of the nc-TiN/a-Si3N4 nanocomposites. Here we show that such impurities also hinder the phase segregation and formation of stable and strong nanostructure consisting of 3-4 nm size TiN nanocrystals "glued" together by about 1 monolayer thick interfacial Si3N4-like layer, thus apparently stabilizing the solid solution at high temperature of more 900C, as reported by other researchers. At the impurity content of only few hundred ppm, the segregation is completed, and a stable nanostructure formed at temperature less 550C. By decreasing the impurity content from 2000-3000 ppm down to about 1000 ppm in an industrial PVD coating equipment, the life time of cutting tools has been increased by a factor of 2.

Supetvrdé nanokompozity,nečistity, kyslík, teplotní stabilita,TiSiN

Superhard Nanocomposites; Impurities; Oxygen; Thermal Stability; TiSiN

24.07.2011

A.J. Drexel Plasma Institute

Philadelphia USA

9241562676

20th International Symposium on Plasma Chemistry http://ispc20.plasmainstitute.org/

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54–57

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