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The surface degradation of metals such as boiler tubes and turbines in high temperature corrosive environments has caused a severe problem in fuel combustion power plant systems. The damage to materials has been often accelerated by mechanical removal of corrosion product formed on the material surface. It is therefore very important to investigate mechanical properties and adhesion of the films in...
With the increasing velocity of vehicles and the fact that the vehicles must fly even in rainy conditions, environmental problems such as rain erosion become more important. Precise specifications are now being set for the rain erosion of materials in the vehicle design.Different attempts have been done to predict the rain erosion resistance of materials from their mechanical properties but this will...
WC–Co coatings were deposited by HVOF spraying from two different feedstock powders, one with a conventionally sized WC grains and one with nanoscale WC grains. The powder feedstock with nanoscale WC grains was employed in the light of published research, which pointed to enhancements in wear resistance associated with nanoscale structures in WC–Co materials. The coatings were subsequently laser remelted...
Abrasive waterjets have been used for many years for the cutting of materials. Abrasive particles are entrained into a rapidly moving jet of water which impinges onto a substrate. Material is removed by erosion processes and the jet fully penetrates the material being cut in a single pass. More recently, abrasive waterjets have been employed for the machining of materials where the abrasive waterjet...
A wide ranging study has been carried out of the forms and mechanisms of failure in solid spheres impacting hard, plane solid surfaces over a range of diameters, impact speed and impact angle. Results illustrated here include examples of soda-lime glass and PMMA. In general the forms of failure observed vary with impact velocity. However, although there is a range of low velocity forms, most materials...
This paper describes the work carried out in assessing the performance of hard chromium, electroless nickel composite and two HVOF tungsten carbide coatings as candidate hard surface coatings for use in offshore gate valves. The coatings were erosion tested in a slurry jet facility and their performance compared with a D-gun 86WC–10Co–4Cr coating that is currently widely used in service. Sand erosion...
In this paper, we propose to create a fractal function defined by an infinite series to model worn surfaces obtained by a grinding process. In this series, each elementary term characterizes a wear process at a given scale. This series is only defined by two parameters: an amplitude parameter and the fractal dimension. This model is tested on worn profiles obtained by using different grinding paper...
An investigation into predicting failure of pneumatic conveyor pipe bends due to hard solid particle impact erosion has been carried out on an industrial scale test rig. The bend puncture point locations may vary with many factors. However, bend orientation was suspected of being a main factor due to the biased particle distribution pattern of a high concentration flow. In this paper, puncture point...
A case study of a unidirectional abrasive metal removal process applied on aluminum flat sheet in manufacturing processes is presented. A series of tests were conducted using belt type abrasive media of varying equivalent grit sizes on both bare and clad aluminum flat sheet. Samples were processed through each media in the longitudinal, transverse and angular orientations with respect to the rolling...
In order to find a link between results obtained from a laboratory erosion tester and tests carried out on a pneumatic conveyor, a comparison has been made between weight loss from bends on an industrial-scale pneumatic conveyor and erosion rates obtained in a small centrifugal erosion tester, for the same materials. Identical test conditions have been applied to both experiments so that comparable...
The tribological behaviour of diamond is highly anisotropic. This is particularly noticeable during conventional diamond polishing, when little or no wear can be detected when the diamond is oriented with certain crystallographic geometries. The topography of polished diamond surfaces indicate that there are two main wear mechanisms associated with diamond polishing at the sliding velocities and pressures...
Micro-scale abrasion (ball cratering) tests were performed with different combinations of ball and bulk specimen materials, under different test conditions, such as load and abrasive slurry concentration. Wear modes were classified into two types: with rolling particle motion and with grooving particle motion. Wear rates observed with rolling particle motion were relatively insensitive to test conditions,...
The tribological properties of the surface of railway tracks have been studied taking into account that the surface layer is composed of sublayers with different microstructures and mechanical properties. The tribological properties of the sublayers have been investigated both in the dynamic and static loading mode. The topmost sublayer is characterized by a very high hardness and the yield stress...
This paper describes the development of an abrasion wear tester to overcome some operational difficulties encountered with a linear abrasion wear tester previously developed at the University of Newcastle, Australia for bulk solids handling applications. These difficulties have been, the large quantity of wear media required, noise from the re-circulating wear media, dust generation and poor reliability...
The erosive wear behavior of selected high chromium white iron and aluminum alloys have been experimentally studied by means of Coriolis wear testing and microscopic examinations. Test results suggested that high chromium white iron and aluminum alloy represent two different groups of metallic materials, “hard-brittle” and “soft-ductile,” which experienced significantly different wear patterns and...
In this work, the influence of the proportion of retained austenite in the abrasive wear resistance of a laser surface melted martensitic stainless tool steel is analysed. Samples of a 0.5wt.% C, 13wt.% Cr+Fe martensitic stainless tool steel were surface melted using a CW CO 2 laser. By changing the processing parameters, samples with proportions of retained austenite varying from 15 to 100%...
This paper investigates the solid particle erosion–corrosion performance of an experimental high velocity oxy-fuel (HVOF) sprayed nickel–aluminium bronze (NAB) coating using conventional gravimetric techniques as well as in situ electrochemical analysis. The coating consists of HVOF powders from three alloys: stainless steel alloy, nickel-based alloy and aluminium bronze alloy. It is a candidate coating...
This work aims to improve the wear resistance of carbide materials by application of PVD hard coatings; chromium and chromium nitride coatings were applied to six types of carbide and their tribological properties were studied. Scratch adhesion strength, micro-abrasion wear resistance and ultra-micro hardness tests of the coatings were held to find a relationship between the tribological properties...
Glass-filled polymers are known to produce considerable wear on the screws and barrels of injection-moulding machines and several coatings and surface treatments have been used to combat this ranging from chromium plating to high velocity oxy fuel (HVOF) WC/Co. However, quantification of the benefits of such coatings and treatments has proceeded on an ad hoc basis and there is little data available...
The progress in developing a new method of assessing material resistance to cavitation erosion is reported. The method proposed incorporates procedures for determining cavitation impingement structure, superposing erosive effects of various cavitation impingement fractions and determining the set of parameters needed to describe material performance under cavitation load of given amplitude distribution...
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