Sliding Wear Test Conditions Research Articles

Sliding wear behavior of a sustainable Fe-based coating and its damage mechanisms

The current industry demand is to identify suitable alternatives to the risk-of-supply prone and/or toxic, WC-Co and electrolytic hard chrome coatings without comprising the desired wear performance. Therefore, compositions based on abundantly available elements (e.g. ‘Fe’) that possess adequate wear resistance are desirable from health, sustainability and economic standpoints. In this work, crystalline Fe-based (Rockit-401) coatings were processed using two different thermal spray routes, i.e. HVOF and HVAF spraying. The influence of deposition route and processing conditions on the microstructure, porosity content, hardness and phase composition was examined. The as-deposited coatings were subjected to mild (5 N) and harsh (15 N) dry sliding wear test conditions by employing alumina ball as the counter surface material, and their wear performance was examined. Mild sliding wear test conditions (5 N) resulted in anomalous wear behavior, where the abrupt drop in CoF at several instances during the test was observed in all the investigated coatings. On the other hand, under harsh wear test conditions (15 N), such an abrupt dip in CoF was not observed. Detailed wear mechanisms of the coatings were revealed under different test conditions (5 N and 15 N). This work sheds light on processing, wear behavior and wear mechanisms of a sustainable and high-performance coating that fulfills non-toxic and sustainability goals in tandem for tribological applications.

Effect of Variation of SiC Reinforcement on Wear Behaviour of AZ91 Alloy Composites.

In this investigation, the extensive wear behaviour of materials was studied using SiC reinforced magnesium alloy composites fabricated through the stir casting process. The wear properties of AZ91 alloy composites with a small variation (i.e., 3%, 6%, 9% and 12%) of SiC particulates were evaluated by varying the normal load with sliding velocity and sliding distance. The worn surfaces were examined by scanning electron microscope to predict the different wear mechanisms on the pin while sliding on the hard disk in the dry sliding wear test condition. The microhardness of the SiC reinforced AZ91 composites was found to be more than the un-reinforced AZ91 alloy. Pins tested at load 19.62 N, and 2.6 m/s exhibited a series of short cracks nearly perpendicular to the sliding direction. At higher speed and load, the oxidation and delamination were observed to be fully converted into adhesion wear. Abrasion, oxidation, and delamination wear mechanisms were generally dominant in lower sliding velocity and lower load region, while adhesion and thermal softening/melting were dominant in higher sliding velocity and loads. The wear rate and coefficient of friction of the SiC reinforced composites were lower than that of the unreinforced alloy. This is due to the fact of higher hardness exhibited by the composites. The wear behaviour at the velocity of 1.39 m/s was dominated by oxidation and delamination wear, whereas at the velocity of 2.6 m/s the wear behaviour was dominated by abrasion and adhesion wear. It was also found that the plastic deformation and smearing occurred at higher load and sliding velocity.

Microstructure and wear properties of multi ceramics reinforced metal-matrix composite coatings on Ti–6Al–4V alloy fabricated by laser surface alloying

ABSTRACTTo improve the wear resistance of titanium alloy, self-lubricating metal-matrix composite coatings reinforced by multi ceramic phases were designed and fabricated by laser surface alloying with the mixed powders of Ni, B4C, graphite and Si3N4 on Ti–6Al–4V alloy. Microstructure and wear resistance of the coatings were investigated. The coatings were mainly composed of TiB2, SiC, TiC0.7N0.3 and the phases containing Ni. There was residual graphite in the coatings. The average hardness of the coatings was 1385–1687 HV, equivalent to 3.7–4.5 times of the substrate. The coatings displayed superior wear resistance under dry sliding wear test condition at room temperature, compared to the substrate (over 13 times better than the substrate). The coating fabricated with the mixed powders of Ni:B4C:C(graphite):Si3N4 = 1:1:1.5:0.2 (mole ratio) exhibited the best wear resistance due to the good matching relationship of the high hardness, good lubrication and certain toughness. The wear mechanism of the coatings was discussed.

Tribological Behavior of Pulsed Electrodeposited Ni-W/SiC Nanocomposites

Ni-14 at.% W/SiC nanocomposite coatings containing 0-6 vol.% of submicron size (0.35 μm) SiC particles were obtained using pulsed electrodeposition technique on mild steel substrate. The coatings were subsequently characterized for uniformity of SiC distribution, grain size and mechanical properties (hardness and elastic modulus) using SEM, XRD and nanoindentation techniques, respectively. It was observed that the SiC particulates were uniformly distributed within the coating. The coating matrix (Ni-W) also exhibited nanograin size. Tribological behavior of Ni-14 W/SiC nanocomposite was analyzed under dry sliding wear test conditions using pin on disk method. The interrelationship between SiC content, interparticle spacing, mechanical properties and wear behavior was analyzed. The results suggest that whereas hardness and modulus of nanocomposite coatings varied with SiC content as per Rule of Mixtures, wear mechanism can be best explained on the basis of Inverse Rule of Mixtures.

Microstructure and Tribological Properties of Mo–40Ni–13Si Multiphase Intermetallic Alloy

Intermetallic compounds are increasingly being expected to be utilized in tribological environments, but to date their implementation is hindered by insufficient ductility at low and medium temperatures. This paper presents a novel multiphase intermetallic alloy with the chemical composition of Mo–40Ni–13Si (at %). Microstructure characterization reveals that a certain amount of ductile Mo phases formed during the solidification process of a ternary Mo–Ni–Si molten alloy, which is beneficial to the improvement of ductility of intermetallic alloys. Tribological properties of the designed alloy—including wear resistance, friction coefficient, and metallic tribological compatibility—were evaluated under dry sliding wear test conditions at room temperature. Results suggest that the multiphase alloy possesses an excellent tribological property, which is attributed to unique microstructural features and thereby a good combination in hardness and ductility. The corresponding wear mechanism is explained by observing the worn surface, subsurface, and wear debris of the alloy, which was found to be soft abrasive wear.

Synthesis and characterization of Ni60-hBN high temperature self-lubricating anti-wear composite coatings on Ti6Al4V alloy by laser cladding

Ni60-hBN composite coatings with varying hBN content were prepared on Ti6Al4V substrates by laser cladding. The composite coatings with no cracks and few pores are bonded metallurgically with the substrates. The phase composition and microstructure of the composite coatings were investigated. The tribological properties of the composite coatings were evaluated under dry sliding wear test conditions at 20°C, 300°C and 600°C, respectively. The microhardness gradually increased from the bottom to the top of the coating and increased with increasing of hBN content. The laser clad Ni60-10%hBN coating exhibits excellent tribological behavior at high temperatures (300°C and 600°C).

An ultra-hard and thick composite coating metallurgically bonded to Ti–6Al–4V

The vacuum braze coating process was proposed to prepare an ultra-hard thick composite coating on titanium alloy in this paper. Mixed powders of Ti–Zr–Cu–Ni and TiC were heated to 1223K and held for 30min under vacuum. Microstructure and mechanical properties of the (Ti–Zr–Cu–Ni)+TiC composite coating have been systematically analyzed. The results showed that a uniform dispersion of TiC in the Ti–Zr–Cu–Ni matrix can be found for the composite coating, which is strongly bonded with TC4. Moreover, the surface hardness improved drastically after the incorporation of TiC particles, and the maximum value of surface Rockwell hardness was 66.1HRC. The (Ti–Zr–Cu–Ni)+TiC composite coating had excellent wear resistance under sliding wear test conditions compared with the pure Ti–Zr–Cu–Ni coating, due to the high hardness of the TiC dispersoids.

Microstructure and Wear Resistance of Fe-Cr-C Hardfacing Alloy Reinforced by Titanium Carbonitride

In order to improve the wear resistance of Fe-Cr-C hardfacing alloy, titanium carbonitride was introduced in situ and a TiC-Tix(C,N)y coating was deposited on the surface of ASTM G3101 steel by a gas metal arc welding process. The microstructure and wear resistance of the hardfacing layer were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), macroscopic hardness meter, spectrometry, and transmission electron microscopy (TEM). The results show that the hardfacing layers mainly consist of (Cr,Fe)7C3, TiC carbides, Tix(C,N)y carbonitrides, and α-Fe (C0.14Fe1.86 and C0.12Fe1.88 martensite) (BCT) in addition to a low content of retained CFe15.1 austenite (FCC). The titanium carbonitride–reinforced coating has high hardness and excellent wear resistance under dry sliding wear test conditions.

지하철 레일의 미끄럼 마모거동을 고려한 재료설계에 대한 고찰

To assess the wear behavior of rails against subway rail car wheels, we investigate the sliding wear behavior of pins derived from two types of rails (normal rails and heat-treated rails) against a disc derived from a subway rail car wheel, using a pin-on-disc-type tribometer. We base the sliding wear test conditions on the sliding conditions for wheel flange-rail gauge corner contact. We demonstrate the remarkable transition in the wear behavior of the pins derived from the rails, from severe wear to mild wear, as a function of the sliding distance. The wear rate of the heat-treated rail material in the running-in wear region is much lower than that of the normal rail material. Furthermore, the wear rates of the pins in the running-in wear region decrease with increasing hardness and with decreasing sliding speed. However, there is little difference between the heat-treated rail pin and the normal rail pin in the wear rate in the steady-state wear region. Stricter controls on the decarburized layer beneath the surface of rails are required to reduce the wear rate in the running-in wear region.

Microstructure and Wear Resistance of AlFeCuCoNiCrTi<sub>1.5</sub> High Entropy Alloy Coating on AZ91D Magnesium Alloys by Laser Cladding

To improve the wear properties of AZ91D magnesium alloys, a AlFeCuCoNiCrTi1.5high entropy alloy (HEA) coating was fabricated on AZ91D magnesium alloys by laser cladding using mixed powders of Al, Fe, Cu, Co, Ni, Cr, and Ti. The microstructure of the HEA coating was characterized by OM, SEM, and XRD. The wear resistance of the HEA coating was evaluated under dry sliding wear test condition at room temperature. The results show that the HEA coating mainly consists of a simple BCC solid solution phase. The HEA coating exhibits excellent wear resistance. The main wear mechanisms of the HEA coating and the AZ91D substrate were different, the former dominated by oxidative abrasive wear and the latter suffered from both adhesive and abrasive wear.

Microstructure and wear resistance of FeAl/Al2O3 intermetallic composite coating prepared by atmospheric plasma spraying

FeAl intermetallic composite coating using Al2O3 as an additive has been fabricated by atmospheric plasma spraying. The microstructure and mechanical properties of the FeAl/Al2O3 composite coating were comparatively studied with those of pure FeAl coating. A uniform dispersion of Al2O3 in the FeAl matrix can be observed for FeAl/Al2O3 composite coating. Moreover, microhardness and adhesive strength improved after the incorporation of Al2O3 particles. The tribological results show that plasma-sprayed FeAl/Al2O3 composite coatings have excellent wear resistance under dry sliding wear test conditions due to the combination of the high yield strength of the intermetallic compound FeAl and the high hardness of the Al2O3 dispersoids.

Microstructure and Wear Resistance of Cu<sub>0.9</sub>NiAlCoCrFe High Entropy Alloy Coating on AZ91D Magnesium Alloys by Laser Cladding

To improve the wear properties of AZ91D magnesium alloys, a Cu0.9NiAlCoCrFe high entropy alloy (HEA) coating was fabricated on AZ91D magnesium alloys by laser cladding using prealloyed Cu0.9NiAlCoCrFe powders. The microstructure of the HEA coating was characterized by OM, SEM and XRD. The wear resistance of the HEA coating was evaluated under dry sliding wear test condition at room temperature. The results show that the HEA coating mainly consists of a simple BCC solid solution phase. The HEA coating exhibits excellent wear resistance. The main wear mechanisms of the HEA coating and the AZ91D substrate were different, the former dominated by oxidative abrasive wear and the latter suffered from both adhesive and abrasive wear.

Development and characterization of laser clad high temperature self-lubricating wear resistant composite coatings on Ti–6Al–4V alloy

To enhance the wear resistance and friction-reducing capability of titanium alloy, a process of laser cladding γ-NiCrAlTi/TiC+TiWC2/CrS+Ti2CS coatings on Ti–6Al–4V alloy substrate with preplaced NiCr/Cr3C2–WS2 mixed powders was studied. A novel coating without cracks and few pores was obtained in a proper laser processing. The composition and microstructure of the fabricated coating were examined by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) techniques, and tribological properties were evaluated using a ball-on-disc tribometer under dry sliding wear test conditions at 20°C (room-temperature), 300°C, 600°C, respectively. The results show that the coating has unique microstructure consisting of α-Ti, TiC, TiWC2, γ-NiCrAlTi, Ti2CS and CrS phases. Average microhardness of the composite coating is 1005HV0.2, which is about 3-factor higher than that of Ti–6Al–4V substrate (360HV0.2). The friction coefficient and wear rate of the coating are greatly decreased due to the combined effects of the dominating anti-wear capabilities of reinforced TiC and TiWC2 carbides and the CrS and Ti2CS sulfides which have excellent self-lubricating property.

Laser cladding of Zr-based coating on AZ91D magnesium alloy for improvement of wear and corrosion resistance

To improve the wear and corrosion resistance of AZ91D magnesium alloy, Zr-based coating made of Zr powder was fabricated on AZ91D magnesium alloy by laser cladding. The microstructure of the coating was characterized by XRD, SEM and TEM techniques. The wear resistance of the coating was evaluated under dry sliding wear test condition at room temperature. The corrosion resistance of the coating was tested in simulated body fluid. The results show that the coating mainly consists of Zr, zirconium oxides and Zr aluminides. The coating exhibits excellent wear resistance due to the high microhardness of the coating. The main wear mechanism of the coating and the AZ91D sample are different, the former is abrasive wear and the latter is adhesive wear. The coating compared to AZ91D magnesium alloy exhibits good corrosion resistance because of the good corrosion resistance of Zr, zirconium oxides and Zr aluminides in the coating.

Toughening and dry sliding wear resistance of Co3Mo2Si alloys

The MgZn2 type Laves phase of Co3Mo2Si has very attractive super high hardness and covalent dominated bonding nature for wear resistance applications. To make it feasible for real application, its inherent brittleness was effectively balanced by toughening it with the ductile cobalt solid solution (Coss) by the laser melting process. The toughening effect was evaluated qualitatively by the observation of the indentation behaviors and the micro-hardness variations of the alloys. The wear properties of the Coss toughened Co3Mo2Si alloys were evaluated in the dry sliding wear test condition at room temperature. Results indicated that the Coss toughened Co3Mo2Si alloys have excellent combination of strength and ductility, and display exceptional wear property.

Performance of Reactive Plasma Cladding TiC Particle Reinforced High Chromium Fe-Based Ceramics Composite Coating

The in-situ synthesized TiC particle reinforced high chromium Fe-based ceramics composite coating was fabricated on the substrate of Q235 steel by plasma cladding process using Fe-Cr-Ti-C composite powder as reactive material. Microstructure of the coating was observed by scanning electron microscope (SEM), the phases were determined by X-ray diffraction (XRD), and the wear resistance was evaluated under dry sliding wear test conditions at room temperature. Results indicate that the composite coating consists of the reinforcing TiC carbide, (Cr,Fe)7C3 eutectic as well as austenite, and is metallurgically bonded to the Q235 steel substrate. The gradient distribution of TiC carbides is observed. TiC particles present in the granular shape in the fusion zone and central zone while present in the dendritic shape on the surface of the composite coating. Hardness of the coating from surface to fusion zone varies a little; the average hardness of the coating is about HV0.2750 which is 3.2 times as much as that of the base. The wear mass loss of Q235 base material is 13 times higher than that of the composite coating.

Microstructure and wear resistance of laser clad TiB–TiC/TiNi–Ti2Ni intermetallic coating on titanium alloy

A wear resistant TiB–TiC reinforced TiNi–Ti2Ni intermetallic matrix composite coating (TiB–TiC/TiNi–Ti2Ni) was prepared on Ti–6.5Al–2Zr–1Mo–1V titanium alloy by the laser cladding process using Ti+Ni+B4C powder blends as the precursor materials. Microstructure and worn surface morphologies of the coating were characterized by optical microscopy (OM), scan electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDS) and atomic force microscopy (AFM). Wear resistance of the coating was evaluated under dry sliding wear test condition at room temperature. The results indicate that the laser clad coating has a unique microstructure composed of flower-like TiB–TiC eutectic ceramics uniformly distributed in the TiNi–Ti2Ni dual-phase intermetallic matrix. The coating exhibits an excellent wear resistance because of combined action of hard TiB–TiC eutectic ceramic reinforcements and ductile TiNi–Ti2Ni dual-phase intermetallic matrix.

Performance of Reactive Plasma Cladding TiC Particle Reinforced High Chromium Fe-Based Ceramics Composite Coating

TheIn SituSynthesized Tic Particle Reinforced High Chromium Fe-Based Ceramics Composite Coating Was Fabricated on the Substrate of Q235 Steel by Plasma Cladding Process Using Fe-Cr-Ti-C Composite Powder as Reactive Material. Microstructure of the Coating Was Observed by Scanning Electron Microscope (SEM), the Phases Were Determined by X-Ray Diffraction (XRD), and the Wear Resistance Was Evaluated under Dry Sliding Wear Test Conditions at Room Temperature. Results Indicate that the Composite Coating Consists of the Reinforcing Tic Carbide, (Cr,Fe)7C3Eutectic as Well as Austenite, and Is Metallurgically Bonded to the Q235 Steel Substrate. the Gradient Distribution of Tic Carbides Is Observed. Tic Particles Present in the Granular Shape in the Fusion Zone and Central Zone while Present in the Dendritic Shape on the Surface of the Composite Coating. Hardness of the Coating from Surface to Fusion Zone Varies a Little; the Average Hardness of the Coating Is about HV0.2750 which Is 3.2 Times as much as that of the Base. the Wear Mass Loss of Q235 Base Material Is 13 Times Higher than that of the Composite Coating.

Effect of molybdenum on microstructure and wear properties of Fe–Ti–Mo–C laser clad coatings

The AISI 1045 steel surface was alloyed with preplaced ferrotitanium (Fe–Ti), ferromolybdenum (Fe–Mo) and graphite powders using a 5 kW CO2 laser. In situ carbide reinforced Fe based surface composite coating was fabricated. The results showed that (Ti,Mo)C particles with flower-like and cubic shapes were formed during laser cladding process. The growth morphology of the reinforcing (Ti,Mo)C carbide has typically faceted features, indicating that the lateral growth mechanism is still the predominant growth mode under rapid solidification conditions. Increasing the amount of Fe–Mo in the reactants led to a decrease in carbide size and an increase in volume fraction of carbide but increased the crack sensitivity of the coating. The multiple carbides of (Ti,Mo)C created a higher microhardness and excellent wear resistance than TiC alone under dry sliding wear test condition.

TiC Particle Reinforced Reactive Plasma Cladding Composite Coating by the Precursor Carbonization-Composition Process

Fe-Cr-Ti-C composite powder was prepared by precursor carbonization-composition process using the mixture of ferrotitanium, chromium, iron powders and precursor sucrose as raw materials. In situ synthesized TiC particle reinforced composite coating was fabricated on substrate of Q235 steel by reactive plasma cladding process using Fe-Cr-Ti-C composite powder. Microstructure of the coating was observed by scanning electron microscope (SEM), the phases in the coating were determined by X-ray diffraction (XRD), and the wear resistance of the composite coating was evaluated under dry sliding wear test conditions at room temperature. Results indicate that the composite coating consists of in-situ the reinforcing TiC carbide, (Cr,Fe)7C3 eutectics and austenitic, and is metallurgically bonded to the Q235 steel substrate. TiC carbide in the composite coating showed the gradient distribution. TiC particles present granular in the fusion zone and central zone, and present dendritic in the surface of the composite coating. Hardness of the coating from surface to fusion zone is little difference, the average hardness of the coating is about HV0.2750, is as 3.2 times as the base. The wear mass loss of Q235 base material is 12 times as that of the composite coating.