Cuprite, paramelaconite and tenorite films deposited by reactive magnetron sputtering

Reactive magnetron sputtering of copper, silver, and gold

Comparative study of niobium nitride coatings deposited by unbalanced and balanced magnetron sputtering

An overview on tailored tribological and biological behavior of diamond-like carbon

Electrical, optical and mechanical properties of sputtered CrNy and Cr1-xSixN1.02 thin films

Although well known and widely used, tools modified with hard coatings are still not applied to the wood industry. Difficulties come from mechanical, physical and tribological properties of wood and of wood based materials together with particular parameters of their processing. The aim of this study was to synthesise hexagonal and cubic chromium nitride coatings and apply them in wood processing to improve cutting tools’ wear resistance. The apparatus used was an industrial type router. The material subjected to cutting was OSB (Oriented Strand Board). The cutting tools with an edge angle of 55° were cemented carbide inserts. The coatings were deposited by triode sputtering system; the hexagonal phase was obtained for 10% of nitrogen in the Ar+N 2 mixture used in the discharge, the cubic one was obtained for a percentage higher than 20%. The composition of coatings was determined by EDS and WDS microanalysis and SEM cross-section observations were performed. The mechanical properties of layers were determined by stress measurements and by a wear test performed with in situ method. It reveals that the most resistant coatings are the Cr 2 N films. These optimal conditions of deposition have been applied to cutting tools in routing process. It appears that CrN or Cr 2 N coatings deposited on both tools’ faces ameliorate significantly tools wear resistance.

CrxNy hard coatings deposited with PVD method on tools for wood machining

The aim of the study was to examine how a modification of the tool surface influences the knives blunting for wood processing. The process was conducted with a laboratory Micro-lathe test apparatus. The cutting tools used in the experiments had an edge angle of 20° and were made of 60SMD8 low-alloy steel and Z90WDCV high-speed steel. The modification of the working surface of the tool involved covering it with antiabrasive coatings: TiN, (Ti,Zr)N, CrXNY W–C:H(DLC) and Cr. 60SMD8 steel was also nitrided. The lowest reduction of the cutting edge has been observed for CrXNY coated knives. The CrXNY coated knives seemed to have the best adhesion to steel, resisting scratching up to 4000 m of the cutting path. The obtained results demonstrate that the modification of a knife with hard coatings delays drawbacks of a knife wearing out processes. The relatively high values of friction coefficient between coatings and wet wood (up to 0.4) require a very large extent of adhesion between coatings and tools surfaces. It seems that for wood rotary peeling with a knife with an edge angle of 20°, it is not enough to increase the edge hardness but it also needs a complete study of the geometry of the edge. It appears that a low value of friction, a good resistance to abrasion and, to some extent, a good adhesion between a coating and a steel knife are the most important factors in wood knife modification.

Antiabrasive coatings: application for wood processing

In the present work CrN films were deposited by magnetron and triode sputtering methods. For the films obtained by both deposition techniques the evolution of the structure and stress versus thickness was studied by a set of analysis methods (e.g. Scanning Electron Microscopy SEM, Scanning Tunnelling Microscopy STM, X-Ray Diffraction XRD, stress measurements). For CrN films deposited by magnetron sputtering a peak of stress appears at a given thickness and the growth direction changes according to the thickness. First, we have tried to understand the behaviour of the intrinsic stress by relating it to their structure. Second, we have explained the observed growth model by a combination between the models of Rickerby and Hones. Finally, we checked this model by a comparison of the films obtained by magnetron and triode sputtering techniques.

Growth mechanism for chromium nitride films deposited by magnetron and triode sputtering methods

Cubic CrN(200) and a mixture of 25% CrN+75% Cr2N(111) coatings were deposited by magnetron sputtering onto carbide tools and tested in wood machining. The composition of the layers was determined by X-ray photoelectron spectroscopy (XPS) analyses. Scanning electron microscopy (SEM) observations showed that Cr2N layers have a columnar structure while CrN layers seem to be featureless. Secondary ion mass spectroscopy (SIMS) profiles have shown a good homogeneity of the layers and no interdiffusion of the different species into the substrate. The mechanical properties of the chromium nitride coatings were characterized by residual stress measurement, hardness measurements and scratch adhesion tests. The layers have some compressive stresses in the range −1.7/−2.1 GPa and −0.4/−1 GPa for CrN and Cr2N, respectively. The more adherent layers are CrN ones which exhibit hardness up to 1900–2100 HV. Cr2N layers are harder (up to 1900–2100 HV) but less adherent. Machining tests were performed up to 5 and 10 km of cutting distance with industrial routers on Oriented Strand Board. Tool wear and service life were compared between the uncoated and coated tools. First, it has been observed that the edge wear is very high, just at the beginning of the routing process. The best result was shown by a carbide tool CrN coated on both faces; the service life of this tool is four times higher than the one of an uncoated tool.

C. Nouveau

Papers

CrxNy hard coatings deposited with PVD method on tools for wood machining

Antiabrasive coatings: application for wood processing

Growth mechanism for chromium nitride films deposited by magnetron and triode sputtering methods

Influence of CrxNy coatings deposited by magnetron sputtering on tool service life in wood processing

Duplex treatment of 32CrMoV13 steel by ionic nitriding and triode sputtering: application to wood machining