ISSN:0267-0844    

DOI:10.1179/sur.1996.12.1.1

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

ISSN:0267-0844    

DOI:10.1179/sur.1996.12.1.3

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

ISSN:0267-0844    

DOI:10.1179/sur.1996.12.1.6

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractDr PETER DEARNLEY of Leeds University reports on the latest in this series of international meetings covering developments in surface engineering processing, technology, and applications and reviews the newly published proceedings.

ISSN:0267-0844    

DOI:10.1179/sur.1996.12.1.37

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

ISSN:0267-0844    

DOI:10.1179/sur.1996.12.1.39

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractCurrent techniques for residual stress measurement can be divided into two general classes: those based on direct measurelnent of the elastic strains in the film using X -ray diffraction; and those based on the associated curvature or deflection of a thin substrate. The most widely used deflection technique is to coat a relatively thin silicon substrate and then measure the curvature of radius resulting from the coating residual stress. However, since this residual stress strongly depends on the substrate material, it is desirable to develop a coating stress measurement technique applicable to any coated material. Thus, the purpose of the present work was to study the feasibility of the deflection technique for residual stress measurements of thin hard coatings on tool materials. This means, in practice, obtaining a suitable technique for mechanical thinning of coated tool materials. Residual stress values obtained using X-ray diffraction data (sin2ψmethod) and literature values of the coating elastic constants were used for comparison. The deflection technique gave compressive residual stress values of 4·]±0·4 and 2·]±0·3 GN m-2in titanium nitride coatings on high speed steel and diamond coatings on cemented carbide respectively. Corresponding values obtainedfrom X-ray measurements were 3·9±0·8 and ]·9±0·4 GN m-2. In summary, the major advantages of the deflection method are that no information about the coating elastic properties is required to calculate the residual stress and that it can be applied to most coated substrates, including technically important materials such as tool steels and cemented carbides.

ISSN:0267-0844    

DOI:10.1179/sur.1996.12.1.43

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractAn interfacial fatigue test technique has been developed to evaluate the contact fatigue behaviour of various coating-substrate systems. It is shown that failure of the coated systems is initiated at the interface and that the intelfacial fatigue limit is a sensitive measure of the bonding condition between the coating and substrate which remains insensitive to the hardness of both materials and the testing conditions. This characteristic of the test is significant in that it allows the separation of bonding strength from other properties of the coating-substrate system. The nature of the test is investigated theoretically in terms of contact mechanics of both homogeneous and layered materials. It is revealed that the shear stress range at the interface is an appropriate parameter for comparing experimental results. Using the critical shear stress range at the interface for coating debonding, the cyclic bonding strengths of various coating-substrate systems can be quantitatively evaluated and compared.

ISSN:0267-0844    

DOI:10.1179/sur.1996.12.1.49

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractThe microstructure and sliding wear properties of a laser clad TiN composite coating on steel 1045 have been investigated using scanning electron microscopy, electron probe microanalysis, X -ray diffraction, and energy dispersive X-ray analysis and a pin-ring dry sliding wear test machine. Excellent fusion bonding with low dilution and absence of cracks has been obtained under laser cladding conditions in which specific energy was in the range 5-20 kJ cm-2and power density was in the range 3·5-5 kW cm-2. The clad layers have been characterised by metallurgical examination, which showed that the bonding zone, which is about 6¨m thick, is aγnickel solid solution growing from the bottom of the molten pool with planar crystal morphology. Particles of TiN,γnickel, and a fine eutectic ofγnickel and (Fe, Cr)23C6in the interdendritic regions have been observed and a large number of TiN particles with irregular shapes remained after laser cladding. Partial dissolution occurred on the edges of the original TiN particulates, growth in which during resolidification was found in the clad region. The TiN reinforced composite coating produced by laser cladding has also been shown to possess good wear resistance.

ISSN:0267-0844    

DOI:10.1179/sur.1996.12.1.55

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractThe wear resistance of austenitic stainless steels can not be adequately improved by conventional plasma nitriding without compromising the corrosion resistance. However, recently a phase, known by some as‘S phase’, based on an alloy of austenitic stainless steel and nitrogen, has shown potential for simultaneously improving wear and corrosion resistance. Coatings of this material were deposited on copper and glass substrates by the reactive magnetron sputtering of AISI 316 targets under various nitrogen partial pressures. The coatings deposited using a single unbalanced magnetron all consisted of fine, spherically tipped columnar grains and showed a characteristic broad X-ray diffraction peak between 45 and 55°2θ. The hardness of these coatings on copper substrates was found to have a maximum value of∼700 HV at∼O.5 mtorr (∼O.7¨bar) nitrogen partial pressure. One coating deposited on glass using two unbalanced magnetrons operating in closed field mode differed from the other coatings, consisting of coarse columnar grains with both rounded and angular surface asperities. The broad X-ray diffraction peak for this coating was shifted to a higher Bragg angle.

ISSN:0267-0844    

DOI:10.1179/sur.1996.12.1.61

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractThe composition of the uppermost surface layer of steel influences the coating properties. Surface segregation is generally considered to be one of the reasons for difficulties that can occur during hot dip galvanising. In the present work the surface composition of cold rolled, batch annealed steels and the change of composition after pickling, polishing, and shot blasting were studied using glow discharge optical emission spectrometry (GDOES) to explain the variations in the reactivity of the steels when undergoing hot dip galvanising. Surface segregation of all the elements included in the measurements (carbon, silicon, manganese, phosphorus, sulphur, chromium, nickel, aluminium, copper, and calcium) was observed. However, only silicon and phosphorus segregation clearly influenced the reactivity of the steel. Steel reactivity during galvanising could not be explained by the segregation of the outermost layer of the steel surface. Some elements (silicon, manganese, and aluminium) can have a relatively thick enrichment zone under the surface and, moreover, silicon concentration profiles can contain two peaks. These findings indicate internal oxidation of these elements, variation of which is a probable explanation for the different behaviour of the steels. Shot blasting, pickling, and polishing clearly influence the reactivity of the steels. Different pretreatments can remove the oxidised unreactive layer and/or increase the concentration of non-oxidised element (silicon). It is evident that the reactivity depends to some extent on the chemical composition of the steel under the topmost surface layer, a zone which is difficult to investigate by surface sensitive analysis methods (Auger spectroscopy, electron spectroscopy for chemical analysis). The present work showed that GDOES is a powerful tool for the analysis of relatively thick surface layers.

ISSN:0267-0844    

DOI:10.1179/sur.1996.12.1.68

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor