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In the present study we show experimental campaign where cavitation erosion in water at different temperatures was investigated. In contrary to other studies, where cavitation is generated by ultrasound, we employed hydrodynamic cavitation, which more closely resembles the conditions in applications – it is known that the results obtained by ultrasonic cavitation can be misleading. The tests were...
Low-temperature interstitial hardening of NiCr alloys by gas-phase carburizing and nitriding increases the coefficient of sliding friction (COF) at low loads by as much as 50%. While the substantial surface hardening provided by the very high concentrations of interstitial carbon or nitrogen tends to decrease the COF, the presence of these interstitial solutes also decreases the thickness of the air-formed...
In monitoring and maintaining machineries, it is extremely important to identify and quantify friction and wear phenomena, for example the progression of wear and the state of friction between sliding surfaces. Because friction and wear processes involve deformation and fracture of materials, they generate elastic stress waves that can be detected and measured as acoustic emission (AE) signals. By...
This study explored a novel method of arranging lubricating dimples on the working surface of thrust bearings. Because these dimples influence the frictional performance of the thrust bearing, we performed experiments to measure the friction coefficient under various dimple arrangements and phyllotactic coefficients. The surface of the experimental thrust bearing was designed to hold CuZn25Al6Mn4...
The dynamic behaviour of bolted joints subjected to axial excitation is investigated using experimental and numerical methods. Firstly, the amount of reduction in clamp force is found by experiments. In addition, the damage of threads is analysed using scanning electron microscope (SEM) and Energy Dispersive X-ray (EDX). Secondly, by changing the tightening torque, the amplitude of the axial excitation,...
The work here described aimed to assess the tribological behaviour of a Ni-matrix-nanocomposite film and to gain understanding of the role that the reinforcing phases play in it. The composite consisted of an array of Ag-coated SnO2 nanowires grown onto a substrate, around which the Ni matrix was galvanostatically deposited. Friction and wear were evaluated under dry sliding conditions using a linearly...
In the present work, the effect of different binder materials on the tribological properties of cemented carbides was studied. Flat samples of conventional WC–Co, and newly developed WC–AISI 304 stainless steel (SS) composites with and without carbon addition were surface finished by grinding and polishing. Comparative experiments were performed using a ball-cratering tribometer. Worn surfaces were...
This paper investigates the effects of surfactants on microhardness, scratch, wear and friction behaviour of the Ni-P-nano-TiO2 composite coatings. Nano TiO2 particles were co-deposited with electroless Ni–P coating on low carbon steel substrates in the presence of anionic and cationic surfactants-sodium dodecyl sulphate (SDS) and dodecyl trimethyl ammonium bromide (DTAB) respectively. Results revealed...
The present work examines the abrasive and the erosive wear performance of WC–12Co microwave clads. Cladding of micrometric and nanometric WC–12Co powders was carried out on austenitic stainless steel substrate using microwave hybrid heating technique. The micrometric clads exhibited the presence of skeleton structured carbides uniformly distributed in the metallic matrix. On the other hand, presence...
The dry grinding of metals is a common machining operation. The main issue with such techniques is metal adhesion on the abrasive tool, which decreases the material removal rate. In this work, the effect of active filler metal loading with materials such as cryolite and KBF4, which are present in the resin of commercial abrasive belts, was studied. Grinding belt experiments and friction tests were...
The tribological behavior of a commercial brake pad material, wear tested under dry sliding conditions against a cast iron counterface disc with a pin-on-disc apparatus, was investigated. Wear tests were conducted at the following disc temperatures: 25°C, 170°C, 200°C, 250°C, 300°C and 350°C. Above 170°C a transition from mild to severe wear was observed. At 25°C and 170°C, the friction layer on the...
This paper investigated the degradation of wire electrode during electrical discharge machining of SiC reinforced Al-based metal matrix composites (MMCs). MMCs with different size of reinforcements (0.7, 3 and 13µm) as well as corresponding matrix material were machined under similar machining conditions to understand the effect of reinforcement size on the degradation of wire. In addition, pulse-on-time...
Fretting wear damage is a concern in heat exchanger tube of Inconel 600 in nuclear power plants. Fretting wear tests of Inconel 600 alloy against stainless steel type 304 were performed for the purpose to identify changes in the wear mechanisms with number of cycles. The results indicated that as cycles increased, the wear volume, worn scar depth and plastic regime at the scar edge first slowly increased,...
This paper compares the stress and strain state simulated in a twin-disc test and a full scale wheel/rail experiment. The simulation is done by two-dimensional finite element models. The simulations regard the scaling factor between these experiments. This factor includes the contact patch size and the deformation depth. Same stresses and strains are calculated for both experiments considering this...
A new form of hybrid texturing is introduced and discussed in terms of friction and wear reduction. Texturing with four pore densities of 5%, 15%, 25%, and 35% was made by laser texturing on steel; the pores were filled with polyphenylene sulfide (PPS) powder followed by curing to form hybrid surface texturing. Ball-on-disk sliding tests were performed under dry conditions at sliding speeds of 0.05,...
In order to balance the strength and lubricating properties of Co matrix alloy at high temperature, Co–Cr matrix high-temperature self-lubricating alloys with addition of molybdenum and silver were fabricated by powder metallurgy technology. The high-temperature tribological behavior of alloys sliding against Si3N4 ceramic ball were investigated by using a ball-on-disc high-temperature tribometer...
Zr-based bulk metallic glasses (BMGs), especially Zr41Ti14Cu12.5Ni10Be22.5, are widely used as mechanical components due to their simple preparation process and excellent properties. In this study, the tribological properties of Zr41Ti14Cu12.5Ni10Be22.5 pins and different counterpart materials (AISI 5120 steel, AISI 52100 steel and Zr41Ti14Cu12.5Ni10Be22.5 amorphous discs) were investigated using...
Changes in temperature can have a large effect on the fretting damage response for materials with properties that are highly temperature sensitive, such as austenitic stainless steel. The fretting damage response of thin sheets of AISI 301 stainless steel in the full hard condition in contact with AISI 52100 steel is investigated for temperatures ranging from 20°C to 250°C. Changes in material resistance...
The state-of-the-art of the thermal barrier coatings (TBCs), used to protect hot path components from combustion gases, is represented by yttria (partially) stabilized zirconia (YPSZ). Combustion and cooling technology improvements in combination with higher turbine inlet temperature imply that the standard YSZ approaches have certain limitations due to sintering and phase transformations at elevated...
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