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

Application of CrAlN coatings on carbide substrates in routing of MDF

This study deals with the development of Chromium Aluminium Nitride (CrAlN) hard coatings (by varying the nitrogen content in the plasma, the target bias voltage, the working pressure and the deposition time) and their characterization by physical and mechanical techniques (XRD, nanoindentation, Young’s modulus, stress, scratch-test, composition, etc.) in order to determine the optimal deposition conditions to apply the coatings to carbide substrates. Moreover, in order to improve the adhesion of the same optimal hard coatings and as it was efficient with Diamond Like Carbon (DLC) coatings, we tried to modify the carbide inserts by chemical attacks with Murakami’s agent before machining. The coated tools (with and without Murakami’s attack) were then tested in routing of Medium Density Fibreboard (MDF). A comparison of the abrasion and shock resistance of the conventional tools with the treated ones, was made. The efficiency of Murakami’s agent was also studied. It was obvious that the coated carbide tools had greater tool life than the untreated ones. Besides, Murakami’s attack was not optimized or not a solution to improve the adhesion of nitride coatings on carbide inserts.Regional Council of Burgundy ISOROY Franc

THE EFFECT OF ANNEALING ON THE PROPERTIES OF ZNO:AL FILMS GROWN BY RF MAGNETRON SPUTTERING

The effect of annealing temperature ranged from 200 to 600 °C on the structural, optical and electrical properties of aluminum doped zinc oxide (ZnO:Al) films was reported. The thin films were deposited on glass and silicon substrates by rf magnetron sputtering method using ZnO target (diameter 7,5 cm) mixed with 2 wt.% Al2O3. It has been found that the crystal structure of ZnO:Al films is hexagonal with c-axis preferential orientation. With an increase in the annealing temperature the intrinsic compressive stress was found to decrease, and near stress-free film was obtained after annealing at 600 °C. A resistivity of 1.25x10-3 cm and an average transmittance above 90 % in visible range were obtained for films prepared at room temperature. 

Effect of duplex treatments by plasma nitriding and triode sputtering on corrosion behaviour of 32CDV13 low alloy steel

This paper presents corrosion behaviour of duplex treated low alloy steel. Different kinds of samples were tested: non-treated, plasma nitrided, ZrBN-triode sputtered and ZrBN-duplex treated samples. The corrosion behaviour was evaluated by electrochemical techniques (corrosion potential and polarisation resistance evolutions versus immersion time, potentiodynamic curves). The corrosion tests were carried out in neutral aqueous saline solution (NaCl 30 g L−1), naturally aerated. The composition and the structure of layers were determined by EDS and XRD, respectively, while the morphology was observed by SEM. Experimental results showed that the corrosion current density Icorr increased with decreasing white layer thickness in plasma nitrided specimens. The nitrides ε-Fe2 − 3N and γ′-Fe4N present in the white layer are nobler than the substrate but may promote, by galvanic effect, a localised corrosion through open porosity. The duplex treated specimens (nitriding+ZrBN coating) present better corrosion protection and enable to overcome the drawbacks of both techniques, mainly the porosity of the deposited films

Determination of the optimum conditions for ion nitriding of 32CDV13 low alloy steel

The excellent mechanical properties of chrome-vanadium low alloy steel usually obviate the need for expensive quench and tempering operations. Furthermore, the presence of a significant amount of nitride phases has generated interest in the applicability of this kind of steel to fabricate tools with good corrosion and wear resistance. In this paper, 32CDV13 low alloy steel was ion nitrided under different process parameters including time (2, 4, 6 and 8 h), temperature (380, 500 and 580 8C) and gas mixture (N2, H2 and CH4). By determining phase composition, hardness profiles, compound layer thickness and case depth, the optimum working conditions were determined. Microhardness tester, X-ray diffraction and scanning electron microscopy were utilised to characterise the nitrided surfaces. The observed differences in the hardness, the thickness and the structure of the compound layers and the diffusion zones are discussed. The optimum results were obtained at 75%N2þ20%H2þ5%CH4 gas mixture, at the temperature of 500 8C and for a process time of 8 h

Amélioration de la durée de service d'outils d'usinage du bois par traitements de surface et préparation de l'arête de coupe

Au travers de ce travail de thèse, nous nous sommes fixé comme objectif, de rechercher des solutions pour augmenter la durée de service des outils de coupe du bois, plus spécialement ceux utilisés en première transformation (usure prématurée et ébréchures des arêtes de coupe). Les améliorations apportées à ces outils en laboratoire proviennent des modifications de surfaces par applications de films durs en couches minces (CrN en l'occurrence) ou bien par traitements thermochimiques (nitruration ionique basse température). Par ailleurs, afin de vérifier l'effet des modifications d'outils sous des conditions réelles d'utilisation, nous avons réalisé du déroulage et fraisage industriel de bois vert, avec des couteaux modifiés en surface par des traitements classiquement utilisés (TiN, CrN, DLC et duplex (nitruration + dépôt dur)). Ces tests d'usinage ont été réalisés dans le cadre d'un projet européen CRAFT. Au regard des résultats obtenus, nous avons ensuite débuté le développement de nouveaux films ternaires (CrAlN et ZrBN) pour un éventuel emploi en usinage du bois. La modification de la géométrie par pré-rodage de l'arête de coupe des couteaux réalisée grâce à un traitement mécanique de sablage a également été étudiée. Pour réaliser cette étude un grand nombre d'équipements de caractérisations physicochimiques et tribologiques des films a été utilisé ainsi que des machines de laboratoire et industrielles d'usinage du bois.The aim of this work is to find solutions to the problems concerning the wood machining tools, especially those employed in first transformation of wood (premature wearing and brooking cutting edge). The obtained improvements of these tools in laboratory can provide from surface modifications by applications of hard thin coatings (like CrN) and thermochemical treatments (low temperature ionic nitriding). Besides, in order to test the efficiency of tools modifications under real machining conditions, we realised industrial peeling and milling of green wood with tools modified by classical treatments and coatings usually employed (TiN, CrN, DLC, duplex treatment (nitriding + hard coating)). These machining tests were realised in frame work of a European CRAFT research project. According to the obtained results, we started to develop new ternary hard coatings (CrAlN and ZrBN) to apply them in wood machining. The modification of the cutting tool's geometry by sand-blasting was also studied. To realise this study, many equipments of physico-chemical and tribological characterization of hard coatings were used as laboratory and industrial wood cutting machines.PARIS-Arts et Métiers (751132303) / SudocSudocFranceF

Cinétique de croissance de nanotubes de carbone mono-parois et multi-parois orientés par procédé plasma

Ce travail est consacré à la synthèse de nanotubes de carbone mono-parois et multi-parois orientés par dépôt chimique en phase vapeur assisté par plasma (PECVD). Des études cinétiques ont montré le rôle spécifique du plasma pour la croissance de nanotubes mono paroi (SWNT) ou possédant peu de parois (FWNT). En effet, les phénomènes de gravure physique et chimique, intrinsèques au procédé PECVD, favorisent la croissance des nanotubes multi-parois, structures plus robustes, au profit des SWNT/FWNT. En optimisant les paramètres du plasma (potentiel plasma, mélange des gaz) et le temps de dépôt, la croissance de SWNT/FWNT orientés peut être réalisée de manière contrôlée. De telles structures peuvent être obtenue à basse température (dès 450C) sur des substrats recouverts d aluminium. Les mesures d émission par effet de champ des SWNT/FWNT orientés montrent des tensions de seuil peu élevées (~5 V. m-1) corrélées avec la morphologie des nanotubes (longueur, rayon). De nombreuses techniques d analyses ont été utilisées pour étudier la structure des nanotubes aussi bien à l échelle locale (microscope électronique à transmission, spectroscopie de perte d énergie) qu à l échelle macroscopique (microscope électronique à balayage, spectroscopie de photoélectrons ultraviolets/X, analyse par détection des atomes de recul, spectroscopie Raman).This work deals with the growth of vertically oriented single- and multi-walled carbon nanotube by electron cyclotron resonance plasma enhanced chemical vapour deposition (ECR-PECVD). The growth kinetics of carbon nanotubes by PECVD have been investigated, highlighting some of the specific aspects of the plasma species on the single or few walled carbon nanotubes (SWNT/FWNT) growth. Controlling the main plasma parameters (plasma potential, gaseous precursor) and growth stages, we have demonstrated that vertically oriented and well separated SWNT or FWNT can be grown. We have demonstrated that such structures can be synthesized on aluminium substrate at temperature as low as 450C. The cold emission measurements on the as-grown SWNT/FWNT show a relative low turn-on voltage (~5 V. m-1), strongly dependent to the nanotubes morphology (length, radius). Nanotubes structural investigations have been conducted as a function of the growth conditions using several analysis, working at local scale (transmission electron microscopy, electron energy loss spectroscopy) as well as macroscopic scale (scanning electron microscopy, X-ray/ultraviolet photoelectron spectroscopy, elastic recoil detection analysis, Raman spectroscopy).NANTES-BU Sciences (441092104) / SudocSudocFranceF

Synthèse de couches minces de nitrures d'aluminium et de Bore par pulvérisation cathodique magnétron classique et à très haute puissance pulsée pour la gestion thermique des composants à haute température de fonctionnement

Ces travaux concernent la mise au point d'un procédé de synthèse de couches minces AIN et BN à basse température par des procédés de pulvérisation réactive. Ce procédé magnétron a été choisi pour sa compatibilité avec les technologies de la microélectronique. Afin de permettre l'élaboration de films très bien cristallisés, nous avons d'une part optimisé le procédé classique et d'autre part mis en œuvre un procédé original en l'occurence la pulvérisation magnétron à très haute puissance pulsée (HiPIMS). Les matériaux obtenus permettront, grâce à leur très forte conductivité thermique, de diminuer la résistance thermique des composants et d'accroître leurs performances.Notre étude à consisté à bien caractériser la décharge en mode DC grâce à des diagnostics in-situ. Une optimisation des nombreux paramètres du plasma en corrélation avec les propriétés des matériaux synthétisés a permis d'obtenir une bonne qualité cristalline des films d'AIN. Par la suite le procédé HiPIMS, non encore utilisé pour le dépôt de matériaux très isolants en plasma réactif d'azote, a été mis en œuvre. Grâce à une amélioration de l'ensemble du procédé, nous avons réussi à lever tous les verrous techniques et à déposer des matériaux très isolants comme l'AIN et le BN. La qualité cristalline des films d'AIN a même été améliorée en comparaison avec la technique conventionnelle (DC) tant bien au niveau de l'interface avec le substrat que dans le volume de la couche. Enfin, les propriétés thermiques des films de nitrure d'aluminium ont été déterminées et liées à leurs microstructures. Une conductivité thermique de 200 W.m-1 .K-1 a été obtenue, valeur proche de celle du matériau massif.This work is dedicaced to the development of a low temperature aluminium and boron nitrides (AIN and BN) thin film deposition process by reactive magnetron sputtering. This process is suitable for the requirement of microelectronics technologies. In order to elaborate high crystalline quality films, we optimized the classical magnetron sputtering process and, then, set-up the newly emerging technique of High Power Impulse Magnetron Sputtering. Thanks to their high thermal conductivities, the synthezided materials will allow a lowering of the thermal resistance of devices and an increasing of their performances. First, a complete analysis of the DC discharge was conducted in order to optimize the numerous plasma parameters in correlation with the material properties. Our study showed that it is possible to obtain a good crystalline quality of aluminium nitride thin films. Second, we have demonstrated for the first time that HiPIMS process, can be used for the deposition of insulating material as AIN and BN. Thanks to an adaptation of the whole process including the pulsed power supply we overcome all technical problems and deposit such dielectric materials. Thanks to time-resolved diagnostic of the discharge, this process was optimised and allowed an improvement of AIN films' crystalline quality both at the interface with the substrate and at the ''bulk'' of the film. Third, thermal properties of AIN films were measured and linked to their microstructures. A thermal conductivity as high as 200 W.m-l.K-1 was obtained.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Effects of thickness variation on properties of ZnO:Al thin films grown by RF magnetron sputtering deposition

International audienc