Excellent Wear Behaviour Research Articles

Evaluation of Microstructure and Hardness of AISI D2 Steel by Time Quenching in Comparison with Water and Oil Quenching

Due to an account of its excellent hardness and wear behavior, AISI D2 is used widely in producing of blanking and cold-forming dies, Punches, Shafts, Studs, and Bolts. Increasing toughness at a fixed high level of hardness is growing requirement for this kind of applications. Improving microstructure characteristics, especially carbides distribution by specific heat treatment, is an appropriate way to meet such requirement. The effect of quenching media on microstructure and hardness of pre-heated and austentized (at 980oC) AISI-D2 tool steel has been studied, and hardness and carbides morphology have been investigated. Three different medias, water, oil and water/oil (time quenching) have been used, then all samples were followed by the same tempering 350oC/1 hour. It has been found that the optimal carbides distribution and optimum hardness have been resulted from a time quenching method.

A case-driven hypothesis for multi-stage crack growth mechanism in fourth-generation ceramic head fracture

BackgroundCeramic bearings are used in total hip arthroplasty due to their excellent wear behaviour and biocompatibility. The major concern related to their use is material brittleness, which significantly impacts on the risk of fracture of ceramic components. Fracture toughness improvement has contributed to the decrease in fracture rate, at least of the prosthetic head. However, the root cause behind these rare events is not fully understood. This study evaluated head fracture occurrence in a sizeable cohort of patients with fourth-generation ceramic-on-ceramic implants and described the circumstances reported by patients in the rare cases of head fracture.MethodsThe clinical survivorship of 29,495 hip prostheses, with fourth-generation ceramic bearings, was determined using data from a joint replacement registry. The average follow-up period was 5.2 years (range 0.1–15.6). Retrieval analysis was performed in one case for which the ceramic components were available.ResultsClinical outcomes confirmed the extremely low fracture rate of fourth-generation ceramic heads: only two out of 29,495 heads fractured. The two fractures, both involving 36 mm heads, occurred without a concurrent or previous remarkable trauma. Considering the feature of the fractured head, a multi-stage crack growth mechanism has been hypothesized to occur following damage at the head–neck taper interface.ConclusionsSurgeons must continue to pay attention to the assembly of the femoral head: achieving a proper head seating on a clean taper is a prerequisite to decrease the risk of occurrence of any damage process within head–neck junction, which may cause high stress concentration at the contact surface, promoting crack nucleation and propagation even in toughened ceramics.

Effects on Micro-Surface Texturing of Mg/B4C Matrix Composites Under Dry Sliding Wear Condition

The predominant objective of this exploration is analyses of the wear conduct of pure Mg and Mg–B4C (5–15%) composites developed by powder metallurgy technique. The elemental map and microscopic examination of the composites were executed by energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM) analysis. Wear conduct of the Mg–B4C composites was investigated at 2000 m sliding faraway with about 30, 60 and 90 N varying loads with and distinct sliding paces of 1, 1.5 and 2 m/s. The wear samples surfaces were explored by SEM, EDS and profilometer analysis. The outcomes establish that the Mg–15% B4C specimen has excellent wear behavior. The Mg–15% B4C composite has significantly minimum specific wear rate than that of Mg and Mg–(5–10%) B4C composites under all load conditions. The surface roughness of Mg decreases from 3.718 to 0.647 µm with increasing of B4C inclusion.

The analysis of the self-lubricating behavior and local failure mechanism of silver-rich solid film

PurposeThe main aim of this paper was to study the self-lubricating behavior and failure mechanism of silver-rich solid film for in-depth analyzing of the friction and wear property of TiAl-10 wt. per cent Ag self-lubricating composite.Design/methodology/approachThe friction and wear property of TiAl-10 wt. per cent Ag self-lubricating composite sliding against Si3N4 ball was tested under the testing conditions of ball-on-disk wear system. Field emission scanning electron microscopy and electron probe microanalyzer were used to analyze the surface morphology of silver-rich solid film. The main element contents were tested by energy dispersive spectroscopy. Silver phase on wear scar could be well identified using X-ray photo-electron spectroscopy. The theory calculation of shearing stress on wear scar was executed to discuss the local failure mechanism of silver-rich solid film. The lubricating role of silver was also discussed to analyze the anti-friction and anti-wear behavior of silver-rich solid film.FindingsThe friction coefficients and wear rates of TASC gradually reduced at 0-65 min, and approached to small values (0.31 in friction coefficient and 3.10×104 mm3N-1m-1 in wear rate) at 65-75 min. The excellent friction and wear behavior of TASC was mainly attributed to the lubricating property of silver-rich film at 65-75 min. At 12→20 N, surface shearing stress increased up to 146.31 MPa, and exceeded more than the shearing strength (125 MPa) of silver-rich film, which caused the propagating of fatigue crack and the destroying of silver-rich film, leading to high friction and severe wear.Originality/valueIt is important that the self-lubricating behavior and local failure of solid film is explored for further understanding the friction and wear property of TiAl alloys.

HVOF-sprayed Coating Over AISI 4140 Steel for Hard Chromium Replacement

The replacement of electrolytic hard chrome (EHC) by high velocity oxy-fuel (HVOF) sprayed coatings is investigated due to the toxicity of EHC process. The wear behavior of AISI 4140 steel coated by HVOF-, EHC-process was compared to quenched and tempered (Q&T) steel using a pin-on-disc apparatus. The wear tests were conducted at room temperature, 10 N applied load and 0.1 m/s sliding speed in dry condition. The results were interpreted on the basis of the microstructure and hardness. Wear micromechanisms were investigated by SEM. The predominant presence of the WC phase and the formation of W2C and W3C phases, associated with decarburization of superheated regions of the CoCr binding phase of HVOF-coated samples were observed by X-ray diffraction analysis. Wear tests results show that the WC-10Co-4Cr coating exhibits better wear resistance than the EHC coating and Q&T steel. The formation of a wear resistant tribolayer was determinant to the excellent wear behavior of the thermally sprayed coating.

Tribological behavior of plastic composites and stainless steel in seawater

The tribological behaviors of poly(tetrafluoroethylene) (PTFE) against 9Cr18Mo, PTFE against glass fiber–epoxy resin (GFER), 316L against PTFE and polyamide 66 (PA66) against PTFE in natural seawater were evaluated in this study by using an MMU-5G friction and wear tester. The tribological test results show that the friction coefficients, seawater temperature and wear rates of the four friction pairs decrease in the following order: PTFE–9Cr18Mo > 316L–PTFE > PTFE–GFER > PA66–PTFE. The images from a confocal laser scanning microscope reveal the wear mechanisms of the four friction pairs during seawater lubrication. The results indicate that the worn surface of 9Cr18Mo exhibits corrosion together with scattered pitting, but the worn surface of 316L is smooth and uncorroded. The worn surface of PTFE for the friction pair of PTFE–GFER is smoother than the original surface. The counterface (GFER) is covered with several PTFE transfer films that help to decrease the friction coefficient and wear rate. During sliding, the friction pair of PA66–PTFE shows excellent wear behavior because the worn surface of PA66 is covered by the PTFE film. The PTFE wear rate significantly increases when the PTFE sliding against 9Cr18Mo occurs in seawater given the serious plastic deformation of PTFE when the surface temperature is increased.

Wear behavior of the aluminum-silicon alloy cylinder liner wear against Chrom–Keramik–Schicht piston ring

The aluminum–silicon alloy cylinder liner shows great potential for engine cylinder liner applications as its excellent castability, light weight, and good thermal conductivity. In order to improve the capability of the whole friction system further, the friction performance of the piston rings wear against cylinder liner should be discussed in details. In this paper, the wear behavior of the aluminum–silicon alloy cylinder liner wear against Chrom–Keramik–Schicht (CKS) piston ring was carried out by the contraposition reciprocating test rig under lubrication. The surface morphology was characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. When CKS piston ring wears against aluminum–silicon alloy cylinder liner, comparing with sprayed molybdenum piston ring, the friction coefficient reduced nearly 10%. Besides, the weight loss of cylinder liner and piston ring reduced nearly 95%. In the process of friction, aluminum was rolled repeatedly on the surface of cylinder liner. And the honing roads were still visible clearly on the worn surface. The coating of CKS piston ring is dense, lower roughness and higher hardness, and not easy to fall off. While the worn surface of CKS piston ring was smooth in the process of adhesive wear. When the aluminum–silicon alloy cylinder liner wears against CKS piston ring, the matched pair presents an excellent wear behavior.

Influence of Two Steps Sintering Parameters on Tribological Behaviour of Hybrid Hydroxyapatite-Based Biocomposites

The nanostructured biocomposites with hydroxyapatite (HAP) matrix reinforced by titanium (Ti), processed by two steps sintering (TSS) route in argon atmosphere, provide excellent wear behaviour when they are elaborated in specific sintering parameters. The wear tests, developed in steel ball-on-disc dry conditions, show low wear rates about 2x10-4 [mm3/Nm] when the biocomposites are processed at 750...8000oC for 450...600 min. in comparison with high wear rates 7x10-4 [mm3/Nm] in 700...7500oC for 300 min. as TSS parameters. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis outline the structural features that explain this wear behaviour.

Tribological studies of potential vegetable oil-based lubricants containing environmentally friendly viscosity modifiers

The amphiphilic properties that result from the fatty acid composition of vegetable oils contribute to a better lubricity and effectiveness as anti-wear compounds than mineral or synthetic lubricant oils. Despite these advantages, vegetable oils show only a limited range of viscosities and this constrains their use as suitable biolubricants in many industrial applications. For the reason, ethylene–vinyl acetate copolymer (EVA) and ethyl cellulose (EC) have been added to the vegetable oil-based lubricants studied. To address this issue, the frictional and lubricant film-forming properties of improved vegetable oil-based lubricants (high oleic sunflower (HOSO), soybean (SYO) and castor (CO) oils), blended with 4% (w/w) of EVA and 1% (w/w) of EC, have been studied. It has been found that castor oil shows the best lubricant properties, when compared to high oleic sunflower and soybean oil, with very good film-forming properties and excellent friction and wear behaviour. This can be attributed to its hydroxyl functional group that increases both the viscosity and polarity of this vegetable oil. Regarding the effect of the viscosity modifiers studied, ethylene–vinyl acetate copolymer exerts a slight effect on lubricant film-forming properties and, thus, helps to reduce friction and wear mainly in the mixed lubrication region. Ethyl cellulose, on the other hand, was much more effective, mainly with castor oil, in improving both mixed and boundary lubrication.

Wear behavior of light-cured resin composites with bimodal silica nanostructures as fillers

To enhance wear behavior of resin composites, bimodal silica nanostructures including silica nanoparticles and silica nanoclusters were prepared and proposed as fillers. The silica nanoclusters, a combination of individually dispersed silica nanoparticles and their agglomerations, with size distribution of 0.07–2.70μm, were fabricated by the coupling reaction between amino and epoxy functionalized silica nanoparticles, which were obtained by the surface modification of silica nanoparticles (~70nm) using 3-aminopropyl triethoxysilane (APTES) and 3-glycidoxypropyl trimethoxysilane (GPS) as coupling agents, respectively. Silica nanoparticles and nanoclusters were then silanized with 3-methacryloxypropyl trimethoxysilane (γ-MPS) to prepare composites by mixing with bisphenol A glycerolate dimethacrylate (Bis-GMA) and tri (ethylene glycol) dimethacrylate (TEGDMA). Experimental composites with various filler compositions were prepared and their wear behaviors were assessed in this work. The results suggested that composites with increasing addition of silica nanoparticles in co-fillers possessed lower wear volume and smoother worn surface. Particularly, the composite 53:17 with the optimum weight ratio of silica nanoparticles and silica nanoclusters presented the excellent wear behavior with respect to that of the commercial Esthet-X, although the smallest wear volume was achieved by Z350 XT. The introduction of bimodal silica nanostructures as fillers might provide a new sight for the design of resin composites with significantly improved wear resistance.

Tuning the Superstructure of Ultrahigh-Molecular-Weight Polyethylene/Low-Molecular-Weight Polyethylene Blend for Artificial Joint Application

An easy approach was reported to achieve high mechanical properties of ultrahigh-molecular-weight polyethylene (UHMWPE)-based polyethylene (PE) blend for artificial joint application without the sacrifice of the original excellent wear and fatigue behavior of UHMWPE. The PE blend with desirable fluidity was obtained by melt mixing UHMWPE and low molecular weight polyethylene (LMWPE), and then was processed by a modified injection molding technology-oscillatory shear injection molding (OSIM). Morphological observation of the OSIM PE blend showed LMWPE contained well-defined interlocking shish-kebab self-reinforced superstructure. Addition of a small amount of long chain polyethylene (2 wt %) to LMWPE greatly induced formation of rich shish-kebabs. The ultimate tensile strength considerably increased from 27.6 MPa for conventional compression molded UHMWPE up to 78.4 MPa for OSIM PE blend along the flow direction and up to 33.5 MPa in its transverse direction. The impact strength of OSIM PE blend was increased by 46% and 7% for OSIM PE blend in the direction parallel and vertical to the shear flow, respectively. Wear and fatigue resistance were comparable to conventional compression molded UHMWPE. The superb performance of the OSIM PE blend was originated from formation of rich interlocking shish-kebab superstructure while maintaining unique properties of UHMWPE. The present results suggested the OSIM PE blend has high potential for artificial joint application.

Tribological Characterization of PVD-Coatings

In cold forging processes the high tribological and mechanical loads often lead to early tool failure. If the cause of failure is wear, an extension of tool life could be achieved by the application of PVD coatings. In industrial tools there is a great variety of load cases that causes wear. Therefore a lot of coatings with different properties are necessary, which need to be adjusted to the various applications. In order to adapt the coatings appropriately to the different processes, a sufficient characterization of the coatings is required. In this paper three new types of PVD coatings based on TiC, AlCrN and TiAlN and two reference PVD coatings based on TiN and TiAlCN are investigated. Since friction plays an important role for the tribological conditions between workpiece and tool, the friction factor m of the coatings is determined for different lubricants in the so called Double Cup Extrusion (DCE) test. A major influence of the lubricants and a minor influence of the coatings can be seen in the conducted tests. Furthermore wear behavior of the coatings is investigated with a so called combined Punching-Forward Extrusion (CPFE) test. In this test it is possible to test simultaneously coated dies and punches under realistic conditions. For the new coating (TiAlN), characterized by monolayer structure, there is wear debris visible in some regions of the die shoulder. The early occurrence of wear might be caused by the ductility of the coating or adherence problems. The other new coatings (TiC and AlCrN), which have a multilayer structure, are revealing excellent wear behavior. The high wear resistance of these two coatings can be explained with their high hardness in combination with a special layer composition.

Alternative bearing materials for intervertebral disc arthroplasty

The objective of our study was to test alternative polymer-on-polymer articulations for cervical total disc arthroplasty with favourable biotribological properties and the benefit of radiolucency in comparison to the clinically well established metal-on-polyethylene coupling. In vitro wear simulation was performed according to ISO 18192-1:2008 ( E) with the clinically introduced activ ® C cervical artificial disc (Aesculap AG Tuttlingen, Germany) made of UHMWPE/CoCr29Mo6 in a direct comparison to experimental disc articulations made of PEEK, CFR–PEEK and PEK. Each material combination was tested for 10 million cycles with a customised 6 station spinal wear simulator (EndoLab Thansau, Germany). Gravimetric and geometric wear assessment, optical surface characterisation and an estimation of particle size and morphology were performed. The gravimetric wear rate of the clinical reference polyethylene-on-cobalt–chromium was 1.0 ± 0.1 mg/million cycles, compared to 1.4 ± 0.4 mg/million cycles for PEEK, to 0.02 ± 0.02 mg/million cycles for CFR–PEEK and 0.8 ± 0.1 mg/million cycles for PEK. In conclusion, a number of different candidate materials for total cervical disc arthroplasty were compared using the same disc design. Whereas the polymer-on-polymer articulation of PEK showed no substantial benefit in comparison to polyethylene-on-cobalt–chromium and whereas natural PEEK tends towards pitting and delamination, the carbon fibre reinforced PEEK demonstrated an excellent wear behaviour with a reduction in order of a magnitude. Therefore, the CFR–PEEK based polymer-on-polymer articulations may be an alternative to polyethylene-on-metal and have a high potential for next generation disc replacements.

Surface Structure Evolution and Abnormal Wear Behavior of the TiNiNb Alloy under Impact Load

The TiNiNb alloy exhibits a linear increase in wear with a number of impacts at the low impact energy density E im of 1.6 J/cm2. However, a change in the volume wear occurs on the wear curve when E im is increased to 2.42 J/cm2. In this case, when the number of impacts N is more than 3 × 105 cycles, the wear rate decreases from 5.8 × 10−6 to 1.9 × 10−6 mm3/cycle, which is only one-half of that under low E im (1.6 J/cm2). It is significant for practical applications because impact energy increases while the wear rate decreases. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses show that a large number of amorphous structures are produced on the sample surface at high E im , while no new crystalline phases appear. The abnormal wear behavior of the TiNiNb alloy can be attributed to the excellent wear behavior of amorphous structure and the consumption of impact energy during amorphous structure production.

Wear Analysis of Functionally Gradient Composite Materials by FE Modelling of Microhardness Measurements and Wear Tests

Rollers of three different material structures were examined: rollers consisting of pure EP resin; homogeneous EP/SiC composite rollers containing 5 vol.% SiC; and EP/SiC composite rollers with functionally gradient (FG) material structure. Wear tests were performed on the rollers. The wear tests showed that rollers of gradient structure are the most wear-resistant of all. Microhardness measurements were performed on the materials of the three different rollers. SEM images were made of the surface of wear traces. In order to get to know better the effect of SiC reinforcement particles on the wear mechanism, microhardness measurements were simulated by 3D FE micro-models. The SEM images and the FE models were used to explain the excellent wear behavior of the tread of rollers with gradient material distribution.

Validation of a New High Performance Alumina Matrix Composite for use in Total Joint Replacement

A new alumina matrix composite ceramic material has been thoroughly evaluated and tested for use as an additional material in the total joint replacement area. The US Food and Drug Administration has approved the material for use in ball heads articulating against polyethylene inserts. Its first clinical use in the United States was in June 2000. Since its introduction, more than 65,000 ball heads of the Alumina Matrix Composite have been implanted. To date, no single clinical failure or material related complication has been reported to the manufacturer. The substantial improvement in mechanical properties and the excellent wear behavior even under severe microseparation wear testing serve to make this material a promising new addition to the orthopedic surgical community.

Influence of the Cup's Edge Geometry on the Transferred Stresses to the Ball/Cup Interface in all Ceramic THR

Alumina ceramics as well as zirconia ceramics have been used to manufacture hip replacement components since the 1990’s. These materials have been used for the ceramic balls and cups in the replacements for the following reasons: in the case of alumina for its excellent wear behavior; and in the case of zirconia, for its good wear behavior but with greater fracture toughness than alumina. Nevertheless, since ceramics are brittle, the design of the components must consider ways to avoid detrimental stress concentrations. In this study the stress concentration on the rim of the ceramic cup is inspected by means of a two-dimensional axis symmetric finite element model. This model simulates contact between the components to obtain the stresses that are transferred from the ball to the cup. Different geometries of the cup’s edge are simulated to evaluate the incidence of the geometry over the stress pattern. Although this model concentrates on the contact between the ball and the cup, the loading is made from the stem to the ball, which means that the load is transferred from the stem to the ball and then to the cup. This approach may offer a more realistic output. The data from this study may be useful for hip replacement designers as well as for surgeons because it shows a direct relationship between the stress patterns and the geometrical parameters of the design.

Hot filament chemical vapour deposition and wear resistance of diamond films on WC-Co substrates coated using PVD-arc deposition technique

Different Cr- and Ti-base films were deposited using PVD-arc deposition onto WC-Co substrates, and multilayered coatings were obtained from the superimposition of diamond coatings, deposited on the PVD interlayer using hot filament chemical vapour deposition (HFCVD). The behaviour of PVD-arc deposited CrN and CrC interlayers between diamond and WC-Co substrates was studied and compared to TiN, TiC, and Ti(C,N) interlayers. Tribological tests with alternative sliding motion were carried out to check the multilayer (PVD + diamond) film adhesion on WC-Co substrate. Multilayer films obtained using PVD arc, characterised by large surface droplets, demonstrated good wear resistance, while diamond deposited on smooth PVD TiN films was not adherent. Multilayered Ti(C,N) + diamond film samples generally showed poor wear resistance. Diamond adhesion on Cr-based PVD coatings deposited on WC-Co substrate was good. In particular, CrN interlayers improved diamond film properties and 6 μm-thick diamond films deposited on CrN showed excellent wear behaviour characterised by the absence of measurable wear volume after sling tests. Good diamond adhesion on Cr-based PVD films has been attributed to chromium carbide formation on PVD film surfaces during the CVD process.

Sliding wear performance of polymer composites under abrasive and water lubricated conditions for pump applications

Bearings made of polymer-based composites are often used when corrosive environments prevent the application of other kinds of materials [N.N., Gleitlager mit Wasserschmierung, Materialwissenschaft und Werkstofftechnik 30 (1999) S243; N.G. Fontana, Corrosion Engineering, second ed., McGraw-Hill, New York, 1978; M. Pourbaix, Lectures on Electrochemical Corrosion, Plenum Press, New York, London, 1973, ISBN 0-306-30449-X]. This is due to the chemical resistance of the polymer matrix and the possibility to tailor the friction and wear properties of such bearings by the use of various types of fillers and fibre reinforcements [R. Prehn, F. Haupert, K. Friedrich, Entwicklung von polymeren Hochleistungsgleitlagerwerkstoffen, in: H.P. Degischer (Hrsg.), Tagungsbandbeitrag 14, Symposium Verbundwerkstoffe und Werkstoffverbunde, Wiley-VCH, Weinheim, 2003, pp. S919–924]. The development of such a material for a journal bearing in pumps, transporting aggressive and abrasive fluids, is the content of this case study. Diverse material compositions were designed and investigated. One was composed of an epoxy resin matrix, highly filled, e.g. with ceramic particles (silicon carbide, i.e. SiC), to combine the ductile character of the polymer with the hardness of the ceramic. It showed an excellent wear behaviour under dry and water lubricated conditions, when operating against steel as the counterpart. Another one consisted of a polyetheretherketone (PEEK) matrix, reinforced with short carbon fibres for sealing applications. Here, an unexpected phenomenon was observed. When the experiments were carried out under water lubrication against a rotating stainless steel ring, the demineralized water strongly affected the wear behaviour of the carbon fibres. It is the purpose of the ongoing study to find out which effects, respectively wear mechanisms, take place in the contact area between both partners, and how the enhanced wear can be reduced under these severe conditions.

Tribological behaviour of the composite PEEK-CF30 at dry sliding against steel using statistical techniques

PEEK is a semi-crystalline polymer. Due to the excellent wear and frictional behaviour this material is widely regarded as the highest performance thermoplastic material currently available. In this work statistical techniques were used to study the effects of pv factor, temperature and sliding distance on the dry sliding tribological behaviour of 30 wt% carbon-fibre-reinforced polyetheretherketone composite (PEEK-CF30). A plan of experiments, based on the combined techniques using orthogonal arrays and ANOVA, was performed on a pin-on-disc machine PLINT TE67HT ®. The obtained results show that friction coefficient was highly influenced by sliding distance factor and, in a smaller degree, by the pv factor. The weight loss was by influenced by the temperature factor and by sliding distance.