http://hdl.handle.net/2117/3138 Sun, 19 May 2013 01:10:40 GMT 2013-05-19T01:10:40Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/14082 Title: Characterisation of laser modified WC-CoCr coatings Authors: Chikarakaraa, Evans; Punset Fusté, Miquel; Picas Barrachina, Josep Anton; Brabazon, Dermot; Naher, S. Abstract: In this work the affects of laser characteristics on surface morphology, microstructure, microhardness and wear rates of high velocity oxygen fuel (HVOF) WC–CoCr coatings were investigated. Continuous and pulsed laser treatments were applied on the HVOF coatings using a CO2 laser of 10.6 μm wavelength. Continuous laser treatment significantly improved homogeneity of the coatings. Pulsed laser treatment produced significantly higher discontinuities compared to continuous mode. Microhardness increased by 45% for continuous mode laser modified WC-CoCr coatings. However, wear resistance deteriorated, with a notable 40% increase in wear rate. The variations in coating properties were attributed to the re-melting and rapid quenching of the CoCr bonding matrix allowing for WC redistribution. Fri, 25 Nov 2011 12:10:43 GMT http://hdl.handle.net/2117/14082 2011-11-25T12:10:43Z Chikarakaraa, Evans; Punset Fusté, Miquel; Picas Barrachina, Josep Anton; Brabazon, Dermot; Naher, S. no In this work the affects of laser characteristics on surface morphology, microstructure, microhardness and wear rates of high velocity oxygen fuel (HVOF) WC–CoCr coatings were investigated. Continuous and pulsed laser treatments were applied on the HVOF coatings using a CO2 laser of 10.6 μm wavelength. Continuous laser treatment significantly improved homogeneity of the coatings. Pulsed laser treatment produced significantly higher discontinuities compared to continuous mode. Microhardness increased by 45% for continuous mode laser modified WC-CoCr coatings. However, wear resistance deteriorated, with a notable 40% increase in wear rate. The variations in coating properties were attributed to the re-melting and rapid quenching of the CoCr bonding matrix allowing for WC redistribution. http://hdl.handle.net/2117/9079 Title: Effect of oxygen/fuel ratio on the in-flight particle parameters and properties of HVOF WC–CoCr coatings Authors: Picas Barrachina, Josep Anton; Punset Fusté, Miquel; Baile Puig, Maria Teresa; Martín Fuentes, Enrique; Forn Alonso, Antonio Abstract: High Velocity Oxy-Fuel (HVOF) spray techniques can produce high performance alloy and cermet coatings for applications that require wear resistant surfaces. In HVOF spraying heat is produced by burning mixtures of oxygen and fuel, mainly hydrogen, kerosene, propane, propylene, natural gas or acetylene. In these processes, the particle velocity and temperature determine the resultant coating properties and in many cases enables a better understanding of the process. The aim of this study is to investigate influences of different oxygen/fuel ratios on velocity and temperature of flying particles as well as properties of the HVOF thermal sprayed WC-CoCr coatings. In this work the feedstock powders were thermally sprayed by two different variants of the high velocity oxy-fuel process, in which the fuels were hydrogen and kerosene. Particle parameters were recorded just prior to impact on the substrate using in-flight particle diagnostic tool Accuraspray-g3®. Detailed correlation of particle parameters and the coating properties is evaluated in order to deduce particle parameter ranges providing coatings with optimum properties. Thu, 23 Sep 2010 18:36:56 GMT http://hdl.handle.net/2117/9079 2010-09-23T18:36:56Z Picas Barrachina, Josep Anton; Punset Fusté, Miquel; Baile Puig, Maria Teresa; Martín Fuentes, Enrique; Forn Alonso, Antonio no HVOF thermal spray, In-flight particle parameters, WC-CoCr, Coatings, Microstructure, Hardness High Velocity Oxy-Fuel (HVOF) spray techniques can produce high performance alloy and cermet coatings for applications that require wear resistant surfaces. In HVOF spraying heat is produced by burning mixtures of oxygen and fuel, mainly hydrogen, kerosene, propane, propylene, natural gas or acetylene. In these processes, the particle velocity and temperature determine the resultant coating properties and in many cases enables a better understanding of the process. The aim of this study is to investigate influences of different oxygen/fuel ratios on velocity and temperature of flying particles as well as properties of the HVOF thermal sprayed WC-CoCr coatings. In this work the feedstock powders were thermally sprayed by two different variants of the high velocity oxy-fuel process, in which the fuels were hydrogen and kerosene. Particle parameters were recorded just prior to impact on the substrate using in-flight particle diagnostic tool Accuraspray-g3®. Detailed correlation of particle parameters and the coating properties is evaluated in order to deduce particle parameter ranges providing coatings with optimum properties. http://hdl.handle.net/2117/7600 Title: Surface finish effect on the anodizing behaviour of Al-Si components obtained by sub-liquidus casting process Authors: Menargues Muñoz, Sergi; Picas Barrachina, Josep Anton; Martín Fuentes, Enrique; Baile Puig, Maria Teresa; Campillo Betbese, Manel; Forn Alonso, Antonio Abstract: The aim of this study was to investigate the hard decorative anodizing components of A357 aluminium alloy, obtained in semisolid state by Sub Liquidus Casting® process, to improve its tribological properties and corrosion resistance. Components were heat treated in order to modify the shape and distribution of the eutectic silicon phase. The influence of shot peening pre-treatment on anodizing process was evaluated. Surface modifications were investigated as they might have beneficial effects on the wear and corrosion behaviour. Furthermore, the influence of surface condition on the anodization colouring behaviour of aluminium was studied. The microstructure and the surface finish influence on the anodic oxide film growth were studied by optical and scanning electron microscopy. Experiments using a tribometer (ball on disc configuration) were performed in order to evaluate the tribological properties of the material. Salt spray corrosion tests were used to study the corrosion properties before and after the anodizing process. Wed, 09 Jun 2010 13:13:11 GMT http://hdl.handle.net/2117/7600 2010-06-09T13:13:11Z Menargues Muñoz, Sergi; Picas Barrachina, Josep Anton; Martín Fuentes, Enrique; Baile Puig, Maria Teresa; Campillo Betbese, Manel; Forn Alonso, Antonio no Semisolid, Sub-liquidus casting, Corrosion, Mechanical properties, Aluminium, Anodizing The aim of this study was to investigate the hard decorative anodizing components of A357 aluminium alloy, obtained in semisolid state by Sub Liquidus Casting® process, to improve its tribological properties and corrosion resistance. Components were heat treated in order to modify the shape and distribution of the eutectic silicon phase. The influence of shot peening pre-treatment on anodizing process was evaluated. Surface modifications were investigated as they might have beneficial effects on the wear and corrosion behaviour. Furthermore, the influence of surface condition on the anodization colouring behaviour of aluminium was studied. The microstructure and the surface finish influence on the anodic oxide film growth were studied by optical and scanning electron microscopy. Experiments using a tribometer (ball on disc configuration) were performed in order to evaluate the tribological properties of the material. Salt spray corrosion tests were used to study the corrosion properties before and after the anodizing process. http://hdl.handle.net/2117/7557 Title: Surface modification of HVOF thermal sprayed WC-CoCr coatings by laser treatment Authors: Chikarakara, E.; Aqida, S.; Brabazon, D.; Naher, S.; Picas Barrachina, Josep Anton; Punset Fusté, Miquel; Forn Alonso, Antonio Abstract: In this work the affects of laser characteristics on microstructure and microhardness of high velocity oxygen fuel sprayed (HVOF) WC–CoCr coatings were investigated. The coating was deposited with a Sulzer Metco WokaJet™-400 kerosene fuel and the laser surface treatments were applied using CO2 laser with 10.6 μm wavelength. Large variations in surface properties were produced from variation in the laser processing parameters. In total, four levels of peak power (100, 200, 300 and 350 W), four levels of spot diameter (0.2, 0.4, 0.6 and 1 mm) and three levels of pulse repetition frequency (PRF) were investigated. An initial set of tests were followed by a more detailed 33 factorial design of experiments. Pulse repetition frequency and duty cycle were set in order to maintain the same overlap in the x and y directions for the raster scanned sample spot impact dimensions. Overlaps of 30% were used in the initial tests and 10% in the more detailed trials. The results have shown that care must be taken to keep the irradiance at a relatively low level compared to uncoated surfaces. High irradiance can in this case result in rough and porous surfaces. Lower levels of irradiance are shown to provide more uniform microstructures, reduced porosity and increased microhardness. Mon, 07 Jun 2010 17:45:38 GMT http://hdl.handle.net/2117/7557 2010-06-07T17:45:38Z Chikarakara, E.; Aqida, S.; Brabazon, D.; Naher, S.; Picas Barrachina, Josep Anton; Punset Fusté, Miquel; Forn Alonso, Antonio no Thermal spraying, Laser surface hardening, WC-CoCr, Tooling In this work the affects of laser characteristics on microstructure and microhardness of high velocity oxygen fuel sprayed (HVOF) WC–CoCr coatings were investigated. The coating was deposited with a Sulzer Metco WokaJet™-400 kerosene fuel and the laser surface treatments were applied using CO2 laser with 10.6 μm wavelength. Large variations in surface properties were produced from variation in the laser processing parameters. In total, four levels of peak power (100, 200, 300 and 350 W), four levels of spot diameter (0.2, 0.4, 0.6 and 1 mm) and three levels of pulse repetition frequency (PRF) were investigated. An initial set of tests were followed by a more detailed 33 factorial design of experiments. Pulse repetition frequency and duty cycle were set in order to maintain the same overlap in the x and y directions for the raster scanned sample spot impact dimensions. Overlaps of 30% were used in the initial tests and 10% in the more detailed trials. The results have shown that care must be taken to keep the irradiance at a relatively low level compared to uncoated surfaces. High irradiance can in this case result in rough and porous surfaces. Lower levels of irradiance are shown to provide more uniform microstructures, reduced porosity and increased microhardness. http://hdl.handle.net/2117/6523 Title: The effect of heat treatment on hardness and drye wear properties of a semisolid processed aluminium alloy Authors: Menargues Muñoz, Sergi; Campillo Betbese, Manel; Baile Puig, Maria Teresa; Picas Barrachina, Josep Anton; Forn Alonso, Antonio Abstract: Semisolid AlSiMg casting alloys are attractive alternatives for automotive and aeronautical applications. In this work the effects of heat treatments on hardness and tribological properties of A356 aluminium alloy obtained by Sub-Liquidus Casting (SLC) were studied. The optimum heat treatment conditions, in which the material presents the maximum hardening and wear resistance values, were determined. Heat treatment conditions investigated included: A356 SLC as cast, T5 and T6. Furthermore, AC-46500 and A6061/T6 were analyzed for comparison. The tribological properties of the samples were investigated by pin-on-disc tests at 5 N and 0.05 and 0.1 m·s-1 in dry conditions. The samples were studied by SEM-EDX techniques in order to determine the wear mechanisms and the determination of the products produced during the tests. The maximum hardness and the lowest dry wear rate were obtained through T6 thermal treatment condition. Tue, 02 Mar 2010 11:52:09 GMT http://hdl.handle.net/2117/6523 2010-03-02T11:52:09Z Menargues Muñoz, Sergi; Campillo Betbese, Manel; Baile Puig, Maria Teresa; Picas Barrachina, Josep Anton; Forn Alonso, Antonio no Semisolid AlSiMg casting alloys are attractive alternatives for automotive and aeronautical applications. In this work the effects of heat treatments on hardness and tribological properties of A356 aluminium alloy obtained by Sub-Liquidus Casting (SLC) were studied. The optimum heat treatment conditions, in which the material presents the maximum hardening and wear resistance values, were determined. Heat treatment conditions investigated included: A356 SLC as cast, T5 and T6. Furthermore, AC-46500 and A6061/T6 were analyzed for comparison. The tribological properties of the samples were investigated by pin-on-disc tests at 5 N and 0.05 and 0.1 m·s-1 in dry conditions. The samples were studied by SEM-EDX techniques in order to determine the wear mechanisms and the determination of the products produced during the tests. The maximum hardness and the lowest dry wear rate were obtained through T6 thermal treatment condition.