Oxide Debris Research Articles

Friction and wear properties of in situ (TiB2+TiC)/Ti3SiC2 composites

Abstract The non-lubricated, ball-on-flat sliding friction and wear properties of in situ (TiB2 + TiC)/Ti3SiC2 composites against bearing steel ball were investigated. The load was varied from 10 to 30 N. The material without TiB2 shows an increasing friction coefficient with the increasing load. However, for (TiB2 + TiC)/Ti3SiC2 composites, the friction coefficient shows an insensitivity to load. Both friction coefficient and wear rate initially increase and then dramatically decrease with TiB2 content increasing from 0 to 20 vol%. (TiB2 + TiC)/Ti3SiC2 composites with 15 vol% and 20 vol% TiB2 show excellent wear resistance, whose friction coefficient and wear rate are much lower than those of TiC/Ti3SiC2 composite. The enhanced wear resistance is mainly attributed to the facts that the hard TiB2 and TiC particles nail the surrounding soft matrix and decentralize the shear stresses under the sliding ball, a self-lubricating oxide debris forms on the wear surface, and the wear mode converts from adhesive wear to abrasive wear.

Wear Characterization of Thermal Sprayed and Fused Fe-Ni-Cr Alloy Coatings with the Addition of CeO<sub>2</sub>

Fe-Ni-Cr alloy powders with CeO2 were flame sprayed and fused on the surface of 1045 carbon steel substrate. The effect of CeO2 on microstructure and tribological behavior of coatings were studied experimentally by means of scanning electron microscopy (SEM), field emission gun scanning electron microscopy (FEGSEM), energy dispersive spectroscopy (EDS) and wear tests. The results show that an adhered oxide debris layer was formed on the worn surface in friction which contributed to decreased wear. Wear rate of the material increased with the load, but dramatically decreased at first and then slightly decreased the sliding speed. The friction coefficient of the material decreased slightly with the load, but increased with sliding speed at first, and then tended to be a constant value. Wear mechanism of the coatings was oxidation wear and a large amount of counterpart material was transferred to the coatings, the RE oxide in the debris layer contributes to the improvement in wear resistance.

Comparative Study on Dry Sliding Wear Behavior of Various Railroad Steels

Understanding the wear behavior of various railroad steels used in different components such as rails, wheels, crossings, and curves has a direct impact on the performance of the rail-wheel system in railroad technology. In the present investigation, the wear behavior of steels having varying microstructures (pearlite, ferrite-pearlite, austenite, and bainite) and different chemical compositions has been studied, utilizing a ball-on-disk sliding tribometer under prototypic load and dry conditions. Results indicate that the wear performance of the steel and the mechanism responsible for its wear are significantly governed by the microstructure as well as changes that occur in the contact region during sliding. The formation of tribo-particles comprising oxides of Fe and their possible smearing resulted in high wear resistance in pearlitic steels with considerable plastic deformation of ferrite lamellae compared with austenitic and bainitic steels. In the case of bainitic steel, the absence of any significant smearing of oxide debris, combined with the presence of some distributed tungsten from the ball, contributed to severe wear. On the other hand, in the case of austenitic steel, third-body abrasion by debris particles, comprising a mix of hard metallic and oxide particles, contributed to severe wear despite its high work-hardening ability. On the whole, the pearlitic steel exhibited superior wear resistance with a lower friction coefficient compared with the bainitic and austenitic steels.

High temperature fretting wear behavior of WC–25Co coatings prepared by D-gun spraying on Ti–Al–Zr titanium alloy

Detonation gun (D-gun) spraying is one of the most promising spraying techniques for producing wear-resistance coatings. A thick layer (about 0.3 mm thickness) of WC–25Co with high hardness was covered on Ti–Al–Zr titanium alloy by D-gun spraying and the fretting wear behavior of WC–25Co coatings was studied experimentally on a high precision hydraulic fretting wear test rig. An experimental layout was designed to perform fretting wear tests at elevated temperatures from room temperature (25 °C) to 400 °C in ambient air. In the tests, a sphere (Si 3N 4 ceramic ball) was designed to rub against a plane (Ti–Al–Zr titanium alloy with or without WC–25Co coatings). It was found that the fretting running regimes of WC–25Co coatings were obviously different from those of Ti–Al–Zr titanium alloy. The mixed fretting regime disappeared in WC–25Co coatings, and the boundaries in the running condition fretting map (RCFM) showed hardly any change as temperature increased. The worn scars were examined using a laser confocal scanning microscope (LCSM), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results showed that the coefficients of friction (COF) of WC–25Co coatings at elevated temperatures were nearly constant in the partial slip regime and very low in the steady state. The fretting damage of the coatings was very slight. In the slip regime, the WC–25Co coatings exhibited a good wear resistance, and the wear volume of the coatings obviously decreased with increasing tested temperature. The fretting wear mechanisms of WC–25Co coatings were delamination, abrasive wear and oxidation wear at elevated temperature. The oxide debris layer formed at higher temperature was denser and thicker on top of WC–25Co coatings, thus providing more surface protection against fretting wear, which played an important role in the low fretting wear of the coatings.

Rare earth effect on the microstructure and tribological properties of FeNiCr coatings

FeNiCr alloys with various amounts of La2O3 powders were thermally sprayed onto steel substrate. Electron probe microscopy analysis (EPMA), X-ray photoelectron spectroscopy (XPS), and an Optimol SRV oscillating friction and wear tester in a ball-on-disc contact configuration were employed to investigate the properties of the sprayed coatings. The results show that rare earth can refine the microstructure effectively and make the element distribution uniform, which leads to the improvement in the properties of the coatings. Meanwhile, the wear rate of the FeNiCr alloy with 1.5% La2O3 is smaller than those of the other coatings. Interestingly, the rare earth can reduce the friction coefficient and act as a self-lubricant in the oxide debris layer formed on the worn surface in friction. The wear mechanism of the coatings is oxidation wear, and a large amount of counterpart material is transferred to the coatings.

Multi-mechanism crack closure simulations in various steels

A multi-mechanism modeling of fatigue crack growth is presented in this paper. The model accounts for the combined effect of plasticity-induced crack closure, oxide-induced crack closure and embrittlement effects near the crack tip. The development of oxide debris behind the crack tip causing oxide-induced crack closure is relevant at low stress intensity factor ranges, in the near-threshold regime. The oxide build-up is empirically modeled to account for fretting oxidation. Embrittlement is assumed to be the result of hydrogen diffusion in the near crack-tip region. Several parametric studies are performed to understand the computing limits of the model. Fatigue crack growth simulations are performed for various steels, and fatigue crack growth rates are determined. The model calculations are shown to match experimental data from literature.

A new delamination pattern in elevated-temperature oxidative wear

The sliding wear tests were performed under the atmospheric conditions at 400 °C for H13 steel. The effects of load on the wear mechanisms and delamination patterns were studied. A new delamination pattern was found to appear in the mild-severe transition region of the elevated-temperature wear. The delamination pattern could be proved by the belt-like debris and the corresponding wide ditches on worn surfaces. Under the loads of 50–100 N, mild oxidative wear prevailed with the characteristics of the plate-like oxide debris and low wear loss and its delamination was from inside oxides or the interface between the oxides and bulk metal. The wear rate increased with increasing load; the mild–severe wear transitions occurred under the loads of 100–200 N concomitant with more and more belt-like debris and wide ditches on worn surfaces. In this case, the wear loss would be mainly attributed to a special delamination from inside the bulk metal underneath the tribo-oxides with the formation of belt-like debris containing oxide and bulk metal. The delamination pattern was realized by the way that the ploughed furrows were first formed by the micro-cutting of oxide particles in the delaminated zone, whereby cracks initiate from the furrow wall and propagate parallel to worn surface to cause the delamination.

A Study on the Properties, Friction, Wear and Adhesion of HVOF Thermal Spray Coating of Micron Size Co-Alloy Powder

High velocity oxygen fuel (HVOF) thermal spray coating of micron size (μ) T800 powder has been studied for the durability improvement of sliding machine components. The optimal coating process (OCP), surface properties, friction, wear behavior and adhesion of HVOF T800 coating have been investigated. The temperature dependence of friction coefficient and wear behavior have been studied at 25°C and at an elevated temperature 538°C (1,000°F) for the study of the temperature effects on FC and wear behaviors of the coating and for the application on high speed air bearing spindle which operates with no lubricants. The OCP was determined from the best surface properties of the 16 OCP searching coatings designed by the Taguchi experimental program of four spray parameters with three levels: a hydrogen flow rate (FR) of 38-42 FMR (1 FMR=12scfh=9.44×10-5 m/s), oxygen FR of 65-70 FMR and feed rate of 30 g/min, and a spray distance of 5 inch. Hardness, roughness and porosity observed from the 16 coatings were 560-640 Hv (5488-6272 MPa), 2.2-3.0 μm and 0.01-0.04% respectively. Friction coefficient (FC) decreased from 5.5-7.0 to 4.8-6.0 with increasing the sliding surface temperature from 25°C to 538°C because of the higher lubrication effect of Co oxide debris at the higher temperature. Wear trace of the coating and counter sliding SUS 304 surface decreased to more than a half with increasing the sliding surface temperature from 25°C to 538°C. Tensile bond strength (TBS) and tensile fracture location (TFL) of Ti64 / T800 were 8,770 psi (60.5 MPa) and near the middle of the coating respectively. Bond coat NiCr did not influence on the TBS of the coating. The adhesion between Ti64 substrate and T800 coating (Ti64/T800) was stronger than the cohesion strength 8,770 psi (60.5 MPa) of T800 coating. These showed that Ti64/T800 coating was recommendable for durability improvement coating on high speed spindle of Ti64.

Effect of transfer layer on dry sliding wear behaviour of cast Al-based composites synthesized by addition of TiO 2 and MoO 3

Two types of composites have been developed by solidification processing by addition of 3, 4, and 5 wt% powders of oxide—TiO 2 and MoO 3, to molten Al-5 wt% Mg alloy. The oxide particles react with the molten alloy resulting in alumina and releasing alloying elements of Ti or Mo. Dry sliding wear behaviour of pins of cast composite, fabricated by solidification of melt-particle slurry in mold, has been determined by pin-on-disc wear tests carried out conventionally and while removing wear debris by camel brush. The accumulated volume loss in composites increases linearly with increasing sliding distance and the wear rate increases more or less linearly with increasing load. Increasing particle content decreases wear rate at a given load. The accumulated volume loss is considerably higher when wear debris is removed by camel brush during dry sliding wear. The nature of the wear debris has been confirmed to be oxidative. The relatively brighter compacted oxide transfer layer could be observed in the SEM micrograph of worn pin surfaces of the composites developed by addition of MoO 3 and TiO 2 respectively. Since the accumulated volume loss in wear is relatively more when the wear debris is removed during dry sliding wear test it may be inferred that wear debris is more beneficial for wear resistance through formation of transfer layer rather than its harmful role in enhancing volume loss through three body wear. At higher loads, the oxide debris are expected to get better compacted to form transfer layer, spread over a larger area of the sliding surface and thus, their removal causes a larger wear compared to that without removal of wear debris. However, a larger cover of transfer layer at higher load does not necessarily imply reduced accumulated volume loss because the wearing process is more aggravated at higher load. Apart from adhesion, micro-cutting and abrasion, the transfer layer also flakes off during dry sliding wear as indicated by the presence of chunky sheet of oxides in wear debris.

On the Occurrences of “Frizzle-Type” Surface Defects in a Hot-Rolled Steel Plate

Metallurgical investigations were directed to probe into the genesis of “frizzle” and fissure-type surface defects on 10-mm hot-rolled steel plates meant for application in flat-bed wagons for carrying heavy machinery. The thin hairline fissures on the steel plates were identified as skin laminations associated with long, shallow, and branched cracks, intruding from the plate surfaces to the interior with curved contours, replete with fragmented oxide scale entrapments and debris. The incidence of these superficial defects on the plates was linked to surface damage to the solidifying skin of continuously cast steel slabs, induced by the extensive pitting and cavitation of caster pinch rolls. It is presumed that during hot rolling of the steel slabs, surface blemishes like indentations and folds got rolled over by metal flow, entrapping copious amounts of primary as well as secondary scales underneath the laminated skin. Under the influence of shear forces during rolling, the defects are believed to have ingressed further into the plate interior leading to the formation of long, shallow, and branched cracks with curved contours and entrapped fragmented oxide scales.

The influence of current load on fretting of electrical contacts

The fretting corrosion behavior of tin coated brass contacts is studied at various current loads (1, 2 and 3 A). The typical characteristics of the change in contact resistance with fretting cycles are explained. The fretted surface is examined using scanning electron microscope, laser scanning electron microscope and energy dispersive analysis of X-rays to assess the surface morphology, extent of fretting damage, extent of oxidation, surface profile and elemental distribution across the contact zone. The degradation of contacts at high and low values of current is explained with reference to the thermal and electrical phenomena occurring at the contact interface. The results showed that irrespective of the current loads under study, the contact resistance is maintained at 1.0±0.02 Ω where the oxide debris formation and the electrical breakdown of oxide particles competed with each other maintaining the equilibrium. The number of cycles to failure of the contacts is delayed at lower current. The fretting corrosion degradation of tin coated contacts occurs much faster at higher currents as it generates more accumulation of oxide wear debris at the contact zone. The observed surface morphology and the tin profile of the fretted surface are in agreement with the experimental results.

Processing optimization, surface properties and wear behavior of HVOF spraying WC–CrC–Ni coating

In this work, the optimal coating process (OCP) designed by Taguchi program for high velocity oxy-fuel (HVOF) thermal spraying WC–CrC–Ni powder on Inconel 718 substrate (IN 718) is obtained by optimizing hardness (38 FMR oxygen flow rate, 53 FMR hydrogen flow rate, 25 g/min powder feed rate and 7 in. spray distance). Oxygen flow rate affects hardness mostly. The surface properties such as microstructure, crystalline phase, hardness, and porosity of WC–CrC–Ni coating have been investigated. The phase of coating has been changed during the OCP spraying because a portion of carbides, such as WC, Cr 7C 3, Ni 3C decomposes to W 2C, Cr, Ni and free carbon. Hardness (1150 ± 50 Hv) and porosity (1.2 ± 0.2%) of the OCP coating have been improved by optimization. The friction and wear behaviors of the WC–CrC–Ni coating, electrolytic hard chrome (EHC) plating and IN 718 have been studied comparatively. The lubrication due to free carbon and metal oxide debris results in a decrease of friction coefficients of the WC–CrC–Ni, compared to EHC and IN 718 at both 25 and 450 °C. It is concluded that HVOF WC–CrC–Ni coating performs more excellent anti-wear than others at both temperatures.

Development of a simple ‘temperature versus sliding speed’ wear map for the sliding wear behaviour of dissimilar metallic interfaces II

The variation in behaviour during sliding wear of Nimonic 80A against Stellite 6 (counterface) at 630 °C, 690 °C and 750 °C and sliding speeds of 0.314 m s −1, 0.405 m s −1, 0.485 m s −1, 0.654 m s −1 and 0.905 m s −1, was investigated. A ‘block-on-cylinder’ configuration was used such that debris retention was not encouraged. At 0.314 m s −1, mild oxidational wear was observed at all three temperatures, due to transfer and oxidation of Stellite 6-sourced debris to the Nimonic 80A. The wear debris particles generated were compacted and readily sintered together to form wear protective ‘glaze’ layers, eliminating metallic contact between the two wear surfaces. Increasing sliding speed above 0.314 m s −1 progressively changed the preferred debris source from Stellite 6 to Nimonic 80A. Oxide debris generation continued at all other sliding speeds and temperatures, however, debris behaviour was highly dependent on sliding speed/temperature combination. At 630 °C, oxide generation was insufficient to eliminate metallic contact, however, was enough to modify and enhance the wear process (i.e. ‘abrasion-assisted-severe-wear’). On raising temperature to 690 °C or 750 °C, greater oxide generation and residency prevented metallic contact and severe wear. At sliding speeds of 0.405 m s −1 (690 °C and 750 °C) and 0.485 m s −1 (750 °C) the still relatively low mobility and high residency of this largely Nimonic 80A-sourced debris was sufficient to allow limited sintering and ‘glaze’ formation and wear levels remained low. Some Stellite 6-sourced Co also improved debris sinterability, most notably at 0.405 m s −1. However, raising sliding speed to 0.485 m s −1 (690 °C), 0.654 m s −1 or 0.905 m s −1 increased debris mobility and reduced residency. The now completely Nimonic 80A-sourced debris tended not to sinter and form ‘glaze’, and instead enhanced wear. Interestingly, oxide generation was more pronounced and wear was lower at 0.905 m s −1 than at 0.654 m s −1, despite the abrasive action and more hostile sliding conditions. The collected data were used to compose a simple temperature versus sliding speed wear map for Nimonic 80A wear when slid against Stellite 6.

Wear characterization of thermal spray welded Ni–Cr–B–Si–RE alloy coatings

The present contribution reports the tribological properties of Ni–Cr–B–Si–RE alloy coatings, thermal spray welded onto steel substrate. A study was conducted that characterized the critical normal loads and sliding speed on the wear behavior of a Ni–Cr–B–Si–RE alloy. The worn surfaces of the Ni–Cr–B–Si–RE alloy coatings were examined with a field emission gun scanning electron microscopy (FEGSEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results show that an adhered oxide debris layer was formed on the worn surface in friction which contributed to decreased wear. Wear rate of the coatings increased with the load, but decreased with the sliding speed in the range of 0.02–0.08 m/s, then increases a little at 0.1 m/s sliding speed. The average friction coefficient is about 0.48, and decreased with the load, but increased with sliding speed at first, and then tended to slight decrease. Wear mechanism is dominated by a large amount of counterpart material transferred to the coating.

High-temperature tribological properties of a cathodic arc ion-plated (V,Ti)N coating

The high-temperature tribological properties of a cathodic arc ion-plated (V,Ti)N coating have been investigated with a SRV high-temperature friction and wear tester. After heating in air at temperatures above 500 °C, V 2O 5 and TiO 2 phases were identified on surfaces of (V,Ti)N coating with V 2O 5-type platelets as the major oxidized product. (V,Ti)N coatings exhibit a friction coefficient in the range of 0.53–1.08 and a wear rate in the range of 1.69 × 10 −7–1.31 × 10 −5 mm 3/Nm, depending on test temperature used. At low temperatures, the presence of oxide debris induced by tribological stressing on the load-bearing regions reduces direct contact between (V,Ti)N coating and Al 2O 3, and generates a mild wear, however, adherent and compacted wear-protective oxide layers are not developed. At temperature of 500 °C or above, the wear-protective oxide layers containing thermally-oxidized V 2O 5 platelets deform plastically to produce a lubricious and smooth appearance to reduce friction. Raman spectroscopy was used to identify the structures of wear debris and coating surfaces after wear tests. Tribochemical reactions are the dominating wear phenomena at low temperatures. The wear debris generated during the wear process consists mainly of the V 2O 5-type tribo-oxides.

Wear-Induced Osteolysis and Synovial Swelling in a Patient With a Metal–Polyethylene Wrist Prosthesis

We present a patient with a metal and polyethylene wrist prosthesis who had recurrent synovial swelling on the volar side of the wrist. Surgical exploration showed synovitis, a severely worn and broken polyethylene insert, polyethylene wear particles, and titanium debris from fretting corrosion. Pathological analysis showed macrophage-phagocytosing polyethylene wear particles and titanium oxide debris. This shows that polyethylene and titanium wear in wrist prosthesis might be a bigger problem than originally believed.

Effect of SiC particles on the friction and wear behavior of Ti 3Si(Al)C 2-based composites

The non-lubricated, sliding friction and wear behavior of Ti 3Si(Al)C 2 and SiC-reinforced Ti 3Si(Al)C 2 composites against AISI 52100 bearing steel ball were investigated using a ball-on-flat, reciprocating tribometer at room temperature. The contact load was varied from 5 to 20 N. For monolithic Ti 3Si(Al)C 2, high friction coefficients between 0.61 and 0.90 and wear rates between 1.79 × 10 −3 and 2.68 × 10 −3 mm 3 (N m) −1 were measured. With increasing SiC content in the composites, both the friction coefficients and the wear rates were significantly decreased. The friction coefficients reduced to a value between 0.38 and 0.50, and the wear rates to between 2.64 × 10 −4 and 1.93 × 10 −5 mm 3 (N m) −1 when the SiC content ranged from 10 to 30 vol.%. The enhanced wear resistance of Ti 3Si(Al)C 2 is mainly attributed to the facts that the hard SiC particles inhibit the plastic deformation and fracture of the soft matrix, the oxide debris lubricate the counterpair, and the wear mode converts from adhesive wear to abrasive wear during dry sliding.

Effect of fretting amplitude and frequency on the fretting corrosion behaviour of tin plated contacts

The fretting corrosion behaviour of tin plated copper alloy contacts at 3, 10 and 20 Hz and at two different track lengths (fretting amplitude) of ±5 and ±25 μm is studied. The change in contact resistance as a function of fretting cycles, surface profile of the contact zone, extent of fretting damage, extent of oxidation and elemental distribution across the contact zone were used to assess the fretting corrosion behaviour. The time to reach a threshold value of contact resistance of 0.1 Ω is found to be early for the track length of ±5 μm compared to that of ±25 μm, at all the three frequencies. For a given track length, this threshold value reaches early at 20 Hz. The roughness and the nature of surface profile suggest considerable amount of oxidation have occurred at the track length of ±25 μm compared to that of ±5 μm. The surface morphology of the fretted zone reveals severe damage of the contact zone for samples with a track length of ±25 μm at all the three frequencies. A pictorial model is proposed to describe the evolution of change in area of the contact zone. Based on the length and width of the contact zone, the fretted area is calculated. The change is fretted area as a function fretting frequency and track length is analyzed. Delamination wear is found to be operative at both track lengths and at all three frequencies. EDX line scanning also indicates higher levels of oxidation at the track length of ±25 μm compared to that of ±5 μm. The variation in the atomic ratios of tin, copper and oxygen of the oxide debris present at the centre and edges of the fretted zone is plotted as an area plot as a function of experimental conditions. The debris is predominantly oxides of copper for the track length of ±25 μm whereas they are mostly oxides of tin for the track length of ±5 μm at all the three frequencies. The narrow and deep surface profile, lower Ra values, overlapping of the tin and copper lines in the EDX line scan and the predominance of oxides of tin support the view that the chances of accumulation of wear debris at the contact zone is very high at the track length of ±5 μm. The study concludes that tin plated contacts could encounter an early failure even at shorter track lengths of ±5 μm, if there is sufficient accumulation of the wear debris at the contact zone.

Tribological properties of flame sprayed Fe–Ni–RE alloy coatings under reciprocating sliding

Fe–Ni–RE self-fluxing alloy powders were flame sprayed onto 1045 carbon steel. The tribological properties of Fe–Ni–RE alloy coatings under dry sliding against SAE52100 steel at ambient conditions were studied on an Optimol SRV oscillating friction and wear tester in a ball-on-disc contact configuration. Effects of load and sliding speed on tribological properties of the Fe–Ni–RE coatings were investigated. The worn surfaces of the Fe–Ni–RE alloy coatings were examined with a scanning electron microscopy(SEM) and an energy-dispersive spectroscopy(EDS). It was found that the Fe–Ni–RE alloy coatings had better wear resistance than the SAE52100 steel. An adhered oxide debris layer was formed on the worn surface in friction. Area of the friction layer varied with variety of sliding speed, but did not vary with load. The oxide layer contributed to decreased wear, but increased friction. Wear rate of the material increased with the load, but dramatically decreased at first and then slightly decreased the sliding speed. The friction coefficient of the material was 0.40-0.58, and decreased slightly with the load, but increased with sliding speed at first, and then tended to be a constant value. Wear mechanism of the coatings was oxidation wear and a large amount of counterpart material was transferred to the coatings.

Studies of high temperature sliding wear of metallic dissimilar interfaces II: Incoloy MA956 versus Stellite 6

The development of wear surfaces formed during limited debris retention sliding wear of Incoloy MA956 against Stellite 6 between room temperature and 750 °C, and sliding speeds of 0.314 and 0.905 m s −1 (7 N applied load, 4522 m sliding distance) were investigated. At 0.314 m s −1, mild oxidational wear was observed at all temperatures, due to oxidation of Stellite 6-sourced debris and transfer to the Incoloy MA956; this debris separated the Incoloy MA956 and Stellite 6 wear surfaces. Between room temperature and 450 °C, the debris mainly took the form of loose particles with limited compaction, whilst between 510 °C and 750 °C the debris were compacted and sintered together to form a Co–Cr-based, wear protective ‘glaze’ layer. The behaviour was identical to that previously observed on sliding Nimonic 80A versus Stellite 6 at 0.314 m s −1. At 0.905 m s −1, mild oxidational wear was only observed at room temperature and 270 °C and dominated by Incoloy MA956-sourced debris. At 390 and 450 °C, the absence of oxide debris allowed ‘metal-to-metal’ contact and resulted in intermediate temperature severe wear; losses in the form of ejected metallic debris were almost entirely Incoloy MA956-sourced. This severe wear regime was also observed from 510 up to 630 °C, but increasingly restricted to the early stages of wear by development of a wear protective Incoloy MA956-sourced ‘glaze’ layer. This ‘glaze’ layer formed so rapidly at 690 °C and 750 °C, that severe wear was all but eliminated and wear levels were kept low. The behaviour observed for Incoloy MA956 versus Stellite 6 at 0.905 m s −1 contrasts sharply with that previously observed for Nimonic 80A versus Stellite 6, in that the Incoloy MA956-sourced high Fe–Cr debris formed a protective oxide ‘glaze’, whilst the Nimonic 80A-sourced Ni and Cr oxides formed an abrasive oxide that at high sliding speeds assisted wear. The data indicates that the tendency of oxide to form a ‘glaze’ is readily influenced by the chemistry of the oxides generated.