Composition Of Wear Debris Research Articles

Effect of the APS YAG coating on the fretting wear properties of Ti60 titanium alloy

To enhance the fretting wear resistance of Ti60 titanium alloy, a YAG coating was applied to the surface using the APS (atmospheric plasma spray) process, followed by an investigation of its fretting wear performance. Nanoindentation technology was employed to evaluate nanomechanical properties, and subsequently, techniques including SEM, EDS, TEM, XRD, XPS, and laser confocal microscopy were utilized to characterize microstructural features of the wear marks and the composition of wear debris. The results indicated that, owing to the presence of the APS YAG coating, the surface nanohardness of the Ti60 titanium alloy increased from 4.4 GPa to 11.06 GPa, while the fretting friction coefficient decreased from 0.186 to 0.155, and the volume wear is reduced by 80.53 %, which significantly improves the fretting wear resistance of Ti60 titanium alloy. As the number of fretting cycles increased, a complete friction layer formed on the surface of the Ti60 titanium alloy, leading to a decrease in fretting friction coefficient and a shift in the wear mechanism. Ultimately, a mixed mechanism was observed involving oxidative wear, abrasive wear, fatigue-induced peeling of the friction layer, and localized plastic deformation. Conversely, the fretting wear mechanism of the APS YAG coating consistently demonstrated abrasive wear, adhesive wear, and fatigue-induced cracking and spalling of the coating.

Fretting fatigue behavior and failure characteristics of 35CrMoA steel under elliptical loading path

Purpose This study aims to understand the multiaxial fretting fatigue, wear and fracture characteristics of 35CrMoA steel under the elliptical loading path. Design/methodology/approach By keeping the contact pressure and torsional shear cyclic stress amplitude unchanged; the axial cyclic stress amplitude varied from 650 MPa to 850 MPa. The fretting fatigue test was carried out on MTS809 testing machine, and the axial cyclic strain response and fatigue life of the material were analyzed. The fretting zone and fracture surface morphology were observed by scanning electron microscope. The composition of wear debris was detected by energy dispersive X-ray spectrometer. Findings In this study, with the increase of axial stress amplitude, 35CrMoA steel will be continuously softened, and the cyclic softening degree increases. The fretting fatigue life decreases unevenly. The fretting scars in the stick region are elongated in the axial direction. The area of fracture crack propagation zone decreases. In addition, the results indicate that wear debris in the slip region is spherical and has higher oxygen content. Originality/value There were few literatures about the multiaxial fretting fatigue behavior of 35CrMoA steel, and most scholars focused on the contact pressure. This paper reveals the effect of axial cyclic stress on fretting fatigue and wear of 35CrMoA steel under the elliptical loading path.

Dry sliding wear behaviour of Ti–6Al–4V pin against SS316L disc in vacuum condition at high temperature

ABSTRACTTi–6Al–4V alloy exhibit a unique combination of mechanical, physical, and chemical properties; that pronounced its desirability for implementation in the fields of aerospace, automobile, and chemical industries. The mechanisms, namely, strain rate response/adiabatic shear band (ASB) – effect of plastic deformation, tribo-chemical reaction and formation of the mechanically mixed layer (MML), can control wear behaviour of the alloy. Hence, the present work investigates the influence of these mechanisms in governing the tribological characteristics of the Ti6Al4V alloy aganist SS316L steel. The experiments were executed on a pin-on-disc tribometer under vacuum (2 × 10−5 Torr), by varying the temperature (25, 100, 200, 300 and 400°C) at constant sliding speed (0.01 ms−1) and load (137.3 N) conditions. Compression test was carried out at distinct strain rate (0.001 and 10 s−1) and temperature (25, 100 and 400°C) values, to investigate the occurrence of ASB. The scanning electron microscopy and energy dispersive X-ray spectroscopy analyses were used to evaluate the formation of appendage layers (oxides and MML) and the composition of wear debris, respectively. The wear rate of the Ti–6Al–4V alloy decreased with increment in temperature (room condition to 400°C) inside vacuum environ, governed by ASB and the presence of oxide layers.

Tribological properties of TiAl-Ti3SiC2 composites

The tribological properties of TiAl-Ti3SiC2 composites (TMC) against Si3N4 ceramic ball pair at room temperature were investigated through the determination of friction coefficients and wear rates, and the morphologies and compositions of wear debris, worn surfaces of TMC and Si3N4 ceramic ball were analyzed. The experimental results showed that TMC with 15wt% Ti3SiC2 exhibited relatively excellent tribological properties. The solid-phase self-lubricating tribo-layers formed on the worn surfaces of both TMC with 15wt% Ti3SiC2 and Si3N4 ceramic ball, which was beneficial to the lower friction coefficient and wear rate.

Friction and Wear Properties of TiAl-Ti3SiC2-MoS2 Composites Prepared by Spark Plasma Sintering

TiAl matrix self-lubricating composites (TMC) with various weight percentages of Ti3SiC2 and MoS2 lubricants were prepared by spark plasma sintering (SPS). The dry sliding tribological behaviors of TMC against an Si3N4 ceramic ball at room temperature were investigated through the determination of friction coefficients and wear rates and the analysis of the morphologies and compositions of wear debris, worn surfaces of TMC, and the Si3N4 ceramic ball. The results indicated that TMC with 10 wt% (Ti3SiC2-MoS2) lubricants had good tribological properties due to the unique stratification subsurface microstructure of the worn surface. The friction coefficient was about 0.57, and the wear rate was 4.22 × 10−4 mm3 (Nm)−1. The main wear mechanisms of TMC with 10 wt% (Ti3SiC2-MoS2) lubricants were abrasive wear, oxidation wear, and delamination of the friction layer. However, the main wear mechanisms of TMC without Ti3SiC2 and MoS2 lubricants were abrasive wear and oxidation wear. The continuous friction layer was not formed on the worn surfaces. The self-lubricating friction layer on the frictional surface, different phase compositions and hardness, as well as density of TMC contributed to the change in the friction coefficient and wear rate.

Friction and wear behavior of NiAl–10 wt%Ti3SiC2 composites

The effect of sliding speed and load on the friction and wear behavior of NiAl–10wt%Ti3SiC2 composites (NAT) at room temperature was investigated through determination of friction coefficients and wear rates in different conditions and analysis of morphologies and compositions of wear debris and worn surfaces of both NAT and Si3N4 ball. The results showed that the friction coefficients decreased and wear rates increased with increase in load, whereas they both decreased with increase in sliding speed. The transition in the wear mode from mild to severe wear was strongly influenced by the sliding speed and load.

Tribological behavior of Ti3SiC2/(WC–10Co) composites prepared by spark plasma sintering

The dry sliding friction and wear behavior of Ti3SiC2/(WC–10Co) composites (TWCs) against GCr15 steel pair at room temperature was investigated through the determination of friction coefficient and wear rate under different conditions and the analysis of the morphologies and compositions of wear debris, worn surfaces of TWC and GCr15 steel. The friction coefficients of TWC with 3wt.% WC–10Co were in the range of 0.40–0.48, and the wear rate varied from 0.6×10−4mm3(Nm)−1 to 1×10−4mm3(Nm)−1. At the load of 10N and sliding speed of 0.353m/s, the glazes were formed on the worn surfaces of TWC. The wear mechanisms were complicated, including micro-cutting and abrasive wear of TWC, oxidation wear of GCr15 steel, as well as adhesive wear caused by the glaze flaking.

Sliding wear behavior of nanocrystalline nickel coatings: Influence of grain size

In the present study the sliding wear behavior of pulse electrodeposited nanocrystalline Ni coatings as a function of grain size including bulk annealed Ni has been systematically studied using pin-on-disc configuration against the WC-Co counter body. The sliding wear has been analyzed with respect to wear rate, coefficient of friction, subsurface deformation and composition of wear debris. The result indicates that the sliding wear rate and coefficient of friction of Ni decreases with decreasing grain size. The subsurface beneath the worn pin surface is composed of a near surface shear region and beneath it a region of bulk plastic deformation. The ratio of the depth of the shear region to the depth of bulk deformed region decreases with decreasing grain size indicating a greater localization of near surface deformation with decreasing grain size.

Wear of Polysilicon Surface Micromachines Operated in High Vacuum

The evolution of wear at sidewall surfaces of polysilicon microelectromechanical systems was investigated in high vacuum under controlled normal load and sliding speed conditions. The static adhesion force was used as an indicator of the changes in wear characteristics occurring during oscillatory sliding contact. Measurements of the static adhesion force as a function of sliding cycles and scanning electron microscopy observations of micromachines from the same batch process subjected to nominally identical testing conditions revealed two distinctly different tribological patterns, namely, low-adhesion/high-wear behavior and high-adhesion/low-wear behavior. The static adhesion force and wear behavior were found to be in direct correlation with the micromachine operational lifetime. Transmission electron microscopy, selected area diffraction, and energy dispersive X-ray spectroscopy yielded insight into the origin, microstructure, and composition of wear debris and agglomerates adhered onto the sliding surfaces. Results demonstrate a strong dependence of micromachine operational life on the removal of the native oxide film and the organic monolayer coating as well as the formation of agglomerates consisting of organic coating material and wear debris.

High-Temperature Wear Properties of the Nitrided Alloys for Steam Turbine Valve System Parts

ASTM A355, SUS422 and Nimonic 901 steel were nitrided and their wear characteristics such as the wear coefficient, amount of wear, shape and composition of wear debris were evaluated. Fe3N and Fe4N were observed in the nitrided layer of ASTM A355. Fe3N, Fe4N and CrN were appeared in the nitride of SUS422. However, only CrN phase was observed in the layer of Nimonic 901. The amount of wear and wear coefficient for the nitride specimen decreased remarkably compared with non-nitrided specimens. Also, the surface hardness and ductility increased and small debris was formed in the nitrided specimen.

ＡＺ９１合金のトライボロジー特性に及ぼす析出組織の影響

The present paper is aiming to examine the tribological properties of Mg-Al-Zn alloy, AZ91. Especially, effect of precipitate morphology on tribological properties, such as wear rate and coefficient of friction, was systematically investigated for cast material. Accelerated aging treatment was carried out at temperatures ranging from 150°C to 300°C for 100 hours after solution-treatment at 413°C for 48 hours. A pin-on-disc wear testing machine was used to evaluate tribological properties at room temperature under dry condition, in which an SUJ2 steel disc was used as the counterface. Vickers hardness after the accelerated aging treatment of AZ91 alloy was about HV80 to HV90. Since the hardness of AZ91 was approximately eight times smaller than that of SUJ2, the dominant wear mechanism was assumed to be abrasive wear. However, the composition of wear debris, rise in temperature during wear tests, change in hardness near the wear surface and macroscopic flow of specimens indicated that the adhesive wear also contributed to the wear properties when the size of precipitates were small or the spacing between precipitates were large. It was suggested that the contribution of adhesive wear increased the wear rate and the coefficient of friction. It was concluded that the wear resistance of AZ91 alloy under dry condition would be improved by densely dispersing the precipitates with sufficiently large size, e.g., precipitates with its length of about 1mm that were observed in materials aged at 200°C.