Comparison of CrAlN layers obtained with one (CrAl) or two targets (Cr and Al) by magnetron sputtering

The authors would like to thank the Regional Council of Burgundy, France for its funding and Michael Walock for his help in English revisionsThe aim of this study is to compare the properties of CrAlN coatings obtained by magnetron sputtering with one (CrAl) or two targets (Cr and Al). The influence of parameters such as the target bias voltage, the working pressure, the deposition time and the bias voltage applied on the Cr or Al targets on the properties of the layers was studied. We characterized the films by X-ray Diffraction, Scanning Electron Microscopy, coupled with Energy Dispersive Spectroscopy, nanoindentation and their residual stresses were also determined. The optimal films obtained with both methods are well crystallized, well-adherent to the substrate, and contained similar amounts of Al (20–30 at.%). The optimal coatings synthesized with one target presented properties not as good as those realized with two targets. Nevertheless, films made with one target showed a lower frictional coefficient probably due to composition control. The lack of compositional control with the use of one target limits the optimization process. With two targets, we have greater control over the film composition. This leads to higher hardness, lower stresses, and improved Young's modulus over films produced with a single CrAl target. Additionally, the morphologies are different (columnar with CrAl and dense with Cr and Al). To conclude, it seems more justified to work if possible with two independent targets.Regional Council of Burgund

Effect of surface finishing such as sand-blasting and CrAlN hard coatings on the cutting edge’s peeling tools’ wear resistance

The authors would like to thank IonBond (Chassieu-France) who made the sand-blasting treatments and the Regional Council of Burgundy and CTBA (Wood and Furniture Technical Centre) for their financial support.The aim of this study is first to define the effect of a surface finishing such as sand-blasting on the geometry of a wood cutting tool and its wear resistance. In addition, the effectiveness of surface coatings like CrAlN deposited by physical vapor deposition (PVD) technique on conventional and sand-blasted cutting edges was studied. A reference tool and different sand-blasted ones were tested by micro-peeling of beech in a laboratory. Microscopic observations, cutting forces measurement and cutting wear tests were carried out to quantify the behavior of these tools. The results obtained showed that the artificial wear by sandblasting leads to an increase in the wear resistance and coating effectiveness, and completely changes the type of damage done to the tools. The sand-blasting application combined or not with CrAlN coating showed an improvement in the wear resistance of the tools and a modification of the forces during the peeling process. The effectiveness of the CrAlN layers was improved thanks to the sand-blasting treatment and then the duplex ones performed better.Regional Council of Burgundy CTBA (Wood and Furniture Technical Centre

Study of the wear behaviour of carbide-tipped tools untreated and CrN-treated in the field of the breaking up of the pine of Alep

This work aims to present an experimental step related to a technique of wood machining in order to evaluate wear for the case of the breaking up of the pine of Alep. In our case the study has been done with one untreated and one CrN-coated carbide tools by magnetron sputtering. The deposition conditions were already optimized in previous studies. The routing machine was equipped with a numerical control RECORD1, manufactured by the Italian firm SCM spa and located at the ENSAM of Cluny.Programme PAI Tassili (2004-2008

Correlation between thermal properties and aluminum fractions in CrAlN layers deposited by PVD technique

The CrAlN coatings are a good alternative to conventional CrN coatings especially for high temperature oxidation-resistance applications. Different CrAlN coatings were deposited on silicon (100) by PVD (Physical vapor deposition) technique from two targets (chromium and aluminum) in a reactive nitrogen atmosphere at aluminum applied negative voltage ( 300, 500, 700 and 900 V). The composition, structural, mechanical and thermal properties of the as-deposited coatings were systematically characterized by energy dispersive analysis of X-rays, X-ray diffraction, nanoindentation, and the ‘‘Mirage effect’’ experiments. The X-ray diffraction (XRD) data show that in general CrAlN coatings were crystallized in the cubic NaCl B1 structure, with the (1 1 1) and (2 0 0) diffraction peaks observed. Two-dimensional surface morphologies of CrAlN coatings were investigated by atomic force microscope (AFM). The results show that with increasing aluminum proportion the coatings became more compact and denser and their increased correspondingly, showing a maximum hardness of about 36 GPa (30 at% of Al) which is higher than that of CrN. Moreover, the results in this work demonstrate that the variation of aluminum fraction alter the resulting columnar grain morphology and porosity of the coatings. However, the thermal properties are greatly affected by these morphological alterations. The correlation between aluminum fraction in CrAlN coatings and its thermal properties revealed that the conductivity and the diffusivity are influenced primarily by size and shape distribution of the pores and secondarily by a decrease of the stitch parameter dimension

Etude de la stabilité thermique et de l’influence de l’épaisseur sur les contraintes de couches de Cr et CrN obtenues par pulvérisation cathodique,

Actes sur CD-Rom pas de version papierCette étude porte sur des dépôts de couches minces dures de chrome et de nitrures de chrome élaborées par PVD et leur caractérisation. Des films de chrome ont été préparés par pulvérisation cathodique RF. L’influence de l’épaisseur des films, de la puissance appliquée à la cible sur les contraintes résiduelles a été étudiée. L’analyse des contraintes résiduelles par le dispositif des Anneaux de Newton, pour différentes épaisseurs, montre l’existence d’un pic de contraintes entre 170 et 200 nm et ce pour une puissance de l’ordre de 200 W ce qui vérifie d’une part les résultats obtenus lors de précédentes études sur BN, AlN ou ZrBN et d’autre part, le modèle de croissance proposé par Nouveau [1]. En effet des analyses en DRX ont été faites afin de vérifier si un changement de structure avait lieu ou pas en fonction de l’épaisseur des couches. Nous nous sommes ensuite intéressés à la stabilité thermique des couches de CrN. Le suivi de recuits sous azote effectués à différentes températures sur des échantillons revêtus de nitrure de chrome par diffraction X montre que la stabilité thermique de ces films est assurée jusqu’à 800°C.Programme PAI TASSILI (France-Algérie) 2004-200

Experimental investigation of the mechanical micro structural and thermal properties of thin CrAIN layers deposited by PVD technique for various aluminum percentages

The thin film of chromium nitride and their derivatives obtained by the filing process physical vapor deposition attract more and more attention from industry given their high resistance to wear. This quality of these coatings may be linked to their good mechanical and tribological properties. Several experimental investigations have led to the development of CrAlN (Chronium Aluminum Nitride) hard coatings by varying the aluminum target bias voltage, in preference to the traditional CrN coating. The present work is based on the investigation of physical and mechanical properties of CrAlN coating deposited on a silicon substrate and the effect of the aluminum proportion on their variation. The results demonstrate that variation in aluminum proportion alters the resulting columnar morphology, porosity and the thermal properties. The correlation between aluminum proportions in CrAlN coatings and his thermal properties revealed that the conductivity and the diffusivity are influenced primarily by size and shape distribution of the pores and secondarily by decrease of the stitch parameter dimension

Usinabilité et effet de la densité sur le profil de l’usure des outils de coupe de WC lors de fraisage de panneaux de MDF

Actes publiés sur un DVD-Rom, pas de version papierLors de l’usinage de MDF (Medium Density Fiberboard), de nombreuses interactions se produisent à l’interface outil/pièce induisant des frottements, des déformations élastiques et plastiques, des réactions chimiques ainsi que l’augmentation de la température de l’outil de coupe, ce qui provoque l’usure de l’arête et par conséquent la dégradation de la qualité du bois usiné. Il existe trois types de MDF de différentes épaisseurs et classés selon leur domaine d’utilisation. Nous nous sommes intéressés à l’usinabilité de trois types de MDF (Standard (E), Hydrofuge (H) et Ignifugé (M)) ainsi qu’à l’effet de paramètres, tels que l’épaisseur et la densité du panneau, sur le profil de l’usure des outils de WC utilisés lors du fraisage de MDF. Les résultats obtenus ont montré que l’usure des outils n’est pas constante le long de l’épaisseur du panneau et qu’elle est en relation avec la densité. Par ailleurs, le MDF Ignifugé M est beaucoup plus abrasif que les deux autres types de MDF

Correlation between thermal properties and aluminum fractions in CrAlN layers deposited by PVD technique

The CrAlN coatings are a good alternative to conventional CrN coatings especially for high temperature oxidation-resistance applications. Different CrAlN coatings were deposited on silicon (100) by PVD (Physical vapor deposition) technique from two targets (chromium and aluminum) in a reactive nitrogen atmosphere at aluminum applied negative voltage ( 300, 500, 700 and 900 V). The composition, structural, mechanical and thermal properties of the as-deposited coatings were systematically characterized by energy dispersive analysis of X-rays, X-ray diffraction, nanoindentation, and the ‘‘Mirage effect’’ experiments. The X-ray diffraction (XRD) data show that in general CrAlN coatings were crystallized in the cubic NaCl B1 structure, with the (1 1 1) and (2 0 0) diffraction peaks observed. Two-dimensional surface morphologies of CrAlN coatings were investigated by atomic force microscope (AFM). The results show that with increasing aluminum proportion the coatings became more compact and denser and their increased correspondingly, showing a maximum hardness of about 36 GPa (30 at% of Al) which is higher than that of CrN. Moreover, the results in this work demonstrate that the variation of aluminum fraction alter the resulting columnar grain morphology and porosity of the coatings. However, the thermal properties are greatly affected by these morphological alterations. The correlation between aluminum fraction in CrAlN coatings and its thermal properties revealed that the conductivity and the diffusivity are influenced primarily by size and shape distribution of the pores and secondarily by a decrease of the stitch parameter dimension

Etude des propriétés microstructurales, mécaniques, thermiques et de la porosité des couches minces de CrAlN déposées par PVD sous différents pourcentages d’aluminium

Several experimental investigations have led to the development of CrAlN (Chrome Aluminum Nitride) hard coatings by varying the aluminum target bias voltage, in preference to the traditional CrN coating. The present work enabled characterisation by physical and mechanical techniques (XRD, AFM, MEB, nano-indentation, Young’s modulus, thermal propriety, Stress, porosity, etc.). Moreover, in order to find improved the adhesion of the different deposition condition of the coatings. The results obtained in this work demonstrate that variation in proportion to aluminum alter the resulting columnar morphology and porosity of the coatings. The thermal properties and the physical property are greatly affected by these morphological alterations. The comparison between the different coating microstructures of CrAlN coatings (columnar and fine-grained) reveals advantages for the fine-grained structure. The results are better wear protection and less profile deviation. Correlation between aluminum proportions in CrAlN coatings and his thermal properties revealed that the conductivity and the diffusivity are influenced primarily by size and shape distribution of the pores and secondarily by decrease of the stitch parameter dimension

Etude de la stabilité thermique et de l’influence de l’épaisseur sur les contraintes de couches de Cr et CrN obtenues par pulvérisation cathodique,

Actes sur CD-Rom pas de version papierCette étude porte sur des dépôts de couches minces dures de chrome et de nitrures de chrome élaborées par PVD et leur caractérisation. Des films de chrome ont été préparés par pulvérisation cathodique RF. L’influence de l’épaisseur des films, de la puissance appliquée à la cible sur les contraintes résiduelles a été étudiée. L’analyse des contraintes résiduelles par le dispositif des Anneaux de Newton, pour différentes épaisseurs, montre l’existence d’un pic de contraintes entre 170 et 200 nm et ce pour une puissance de l’ordre de 200 W ce qui vérifie d’une part les résultats obtenus lors de précédentes études sur BN, AlN ou ZrBN et d’autre part, le modèle de croissance proposé par Nouveau [1]. En effet des analyses en DRX ont été faites afin de vérifier si un changement de structure avait lieu ou pas en fonction de l’épaisseur des couches. Nous nous sommes ensuite intéressés à la stabilité thermique des couches de CrN. Le suivi de recuits sous azote effectués à différentes températures sur des échantillons revêtus de nitrure de chrome par diffraction X montre que la stabilité thermique de ces films est assurée jusqu’à 800°C.Programme PAI TASSILI (France-Algérie) 2004-200