Wear Resistance Of Titanium Alloy Research Articles

Influence of thermal oxidation duration on the microstructure and fretting wear behavior of Ti6Al4V alloy

Thermal oxidation under water oxidizing atmosphere was performed on Ti6Al4V alloy under different durations from 2 h to 8 h. Surface characterizations were performed using X-ray diffractometery (XRD), scanning electron microscopy (SEM), Raman spectroscopy, nanoindentation and nano scratch testing. Fretting wear behaviors of untreated and oxidized samples were also examined. The formed oxide coating mainly included rutile TiO2 as well as a little alumina. The weight gain with respect to the oxidation duration obeyed the linear oxidation kinetics law. The growth of oxide grains was in inadequate growth state of incomplete scale coverage from 2nd to 4th hour duration, in normal growth state from 4th to 6th hour duration while in excessive growth state of oxide particle agglomeration and surface roughening from 6th to 8th (or more than 8th) hour duration. The coating thickness increased from 5 μm to 12 μm as oxidation duration increased from 2 h to 8 h. The increase in duration also increased surface roughness and nano hardness as well as adhesion strength of the film/substrate for oxidized samples. The nano hardness value was 10.06 ± 2.15 GPa and the critical load of failure during nano scratch testing was 554.3 ± 6.44 mN for 4 h treated sample. The untreated and oxidized samples showed a same fretting running status and fretting regime with a displacement amplitude of 200 μm while revealing different fretting failure mechanisms. It was mainly abrasive and adhesive wear under ploughing force for untreated sample, while a mix of 3-body abrasion by rolling oxide particles and severe plastic deformation under high contact stress between two ceramic materials for the oxidized samples. The oxide coating was not worn out and improved the fretting wear resistance of titanium alloy.

Ti-6Al-4V 合金の大気酸化挙動に及ぼす微粒子ピーニングの影響

The effect of a fine particle peening (FPP) on atmospheric oxidation behavior and tribological properties of Ti-6Al-4V alloy was evaluated. Surface microstructures of oxidized specimens pre-treated with FPP were characterized using scanning electron microscope (SEM), energy dispersive spectrometry (EDS), glow discharge optical emission spectrometry (GDOES) and X-ray diffraction (XRD). The oxide layer formed on the oxidized specimen pre-treated with FPP was thicker than that on the oxidized-only specimen, because the microstructure induced by FPP facilitated the diffusion of oxygen and aluminum elements during the oxidation process. As results of reciprocating sliding wear tests, width of wear track on the oxidized specimen pre-treated with FPP was shallower compared to the oxidized-only specimen. Moreover, the oxide layer formed at the oxidized-only surface was delaminated during tests, otherwise there was no delamination at the oxidized surface pre-treated with FPP. This was because the surface oxide layer exhibited good interface adherence due to the existence of a thick oxygen solid solution layer. These results indicate that the modified layer created by the combination process of FPP and atmospheric oxidation is effective to improve the wear resistance of titanium alloys.

Thermal oxidation of Ti6Al4V alloy and its biotribological properties under serum lubrication

The purpose of this work was to develop a thermal oxidation technique to improve the wear resistance of titanium alloy for the application of biomedical field. It was found that rutile TiO2 film was formed on the surface of titanium alloy after thermal oxidation at 700°C in a gas mixture of nitrogen with 40% oxygen by volume ratio. The nanohardness of TiO2 film was 21.11GPa, 299.1% higher than that of titanium alloy. The biotribological test revealed that thermal oxidized titanium alloy exhibited low friction coefficient and high wear resistance, which indicated that the thermal oxidized titanium alloy could be a potential candidate for artificial joints.

Wear resistant multilayer nanocomposite WC1−x/C coating on Ti–6Al–4V titanium alloy

A significant improvement of tribological properties on Ti–6Al–4V has been achieved by developed in this study multilayer treatment method for the titanium alloys. This treatment consists of an intermediate 2μm thick TiCxNy layer which has been deposited by the reactive arc evaporation onto a diffusion hardened material with interstitial O or N atoms by glow discharge plasma in the atmosphere of Ar+O2 or Ar+N2. Subsequently, an external 0.3μm thin nanocomposite carbon-based WC1−x/C coating has been deposited by a reactive magnetron sputtering of graphite and tungsten targets. The morphology, microstructure, chemical and phase compositions of the substrate material after treatment and coating deposition have been investigated with use of AFM, SEM, EDX, XRD, 3D profilometry and followed by tribological investigation of wear and friction analysis. An increase of hardness in the diffusion treated near-surface zone of the Ti–6Al–4V substrate has been achieved. In addition, a good adhesion between the intermediate gradient TiCxNy coating and the Ti–6Al–4V substrate as well as with the external nanocomposite coating has been obtained. Significant increase in wear resistance of up to 94% when compared to uncoated Ti–6Al–4V was reported. The proposed multilayer system deposited on the Ti–6Al–4V substrate is a promising method to significantly increase wear resistance of titanium alloys.

Surface Modification of Ti6Al4V by Plasma Copper and Nickel Alloying Process

Abstract Plasma surface copper and nickel alloying was applied to Ti6Al4V alloy. The effects of treatment temperatures on the microstructures were investigated by scanning electron microscope (SEM). The chemical composition and phase constituents of the alloyed layer were analyzed using glow discharge spectrum (GDS) and X-ray diffraction (XRD). The results show that the alloyed layer prepared at 850 °C with about 7 μm in thickness is bonded strongly to the Ti6Al4V substrate and consists of unbound Ti, Ti 2 Ni, TiNi, Cu 0.81 Ni 0.19 and CuTi. The results indicate that the treated samples exhibit excellent antibacterial properties within 12 h. The wear resistance of titanium alloy is also improved.

Crack Initiation and Fatigue Behaviour Evaluation of Ceramic Film Deposited on Ti-6Al-4V Alloy

Titanium alloy offers several material properties including strength-to-weight ratio and good fatigue properties. Wear resistance of Titanium alloy is comparatively lower. To improve its wear resistant properties surface treatment must be considered. Hard thin film deposited by PVD technique is well-known to improve the wear resistance. In this study, ceramic film (CrN) was applied to titanium alloy and its effect on the fatigue behavior was investigated. Substrate material for this work was Ti-6Al-4V. As the film hardness, crystal orientation and surface morphology were strongly depended on the bias voltage during the deposition, the ceramic film was deposited by arc ion plating (AIP) method at two different negative bias voltages. Tension-tension fatigue test and tensile test were carried out to investigate the fatigue properties. As the result, the fatigue strength was influenced by the deposition of the ceramic film, especially; the fatigue strength was remarkably decreased by the deposition of the ceramic film at high negative bias voltage compared to the uncoated specimen and the deposition of the ceramic at low negative bias voltage. On the basis of crack initiating behavior during fatigue test and tensile test the difference of the fatigue strength was also investigated.

Surface modification of Ti-6Al-4V alloy by cathode assiting discharge setup and conventional plasma nitriding methods

In order to improve the wear resistance of titanium alloys, the potential of the plasma nitriding process with a cathode assiting discharge setup was examined. Ti6Al4V alloy was nitrided by the cathode assiting discharge nitriding (CAN) and conventional DC plasma nitriding (CPN) methods, respectively. The micro-topography, phase composition and cross-sectional microhardness distribution of two nitriding layers were studied comparatively. The sliding wear resistance of the nitriding layers was examined by a ball-on-disk test against Si3N4 balls. The results indicated that the surface roughness Ra of the CAN layer was about 1 order less than that of the CPN layer. In addition, the CAN surfaces possessed significantly greater wear resistance than the CPN layer at higher loads, and increased the wear resistance of Ti6Al4V alloy by about 2 orders due to the higher loading bearing ability, higher rate of TiN phase, greater surface microhardness and bigger microhardness improving depth. This is because the double glow discharge effect in CAN strengthened the density of the active nitrogen atoms and the nitriding efficiency. Moreover, the ion bombardment effect on the surface of the nitriding titanium alloy was reduced obviously.

Microstructural characteristics of SiC-B4C reinforced laser alloying composite coatings

Abstract A hard SiC-B4C reinforced composite coating was fabricated by laser alloying of SiC-B4C+Al-Sn-Mo-Y2O3 mixed powders on a Ti-3Al-2V alloy. Al-Sn-Mo mixed powders were first used in the laser alloying technique to improve the wear resistance of titanium alloys. Proper selection of the laser alloying process parameters allows us to obtain a composite coating with a metallurgical combination with substrate. Under the action of Mo, fine particles with high microhardness were produced in the coating matrix and also hindered the formation of adhesion patches and deep plowing grooves during the sliding wear process, leading to the improvement of wear resistance of a titanium alloy substrate surface.

Friction Stir Surfacing Route: Effective Strategy for the Enhancement of Wear Resistance of Titanium Alloy

Titanium alloys are widely used in aerospace applications due to their properties like high strength to weight ratio, good corrosion and creep resistance. Poor wear resistance of these alloys limits their use in tribological applications. Friction surfacing technique is now recognized as an effective solution to surface engineer the light weight high strength alloys to make them suitable for general engineering applications involving wear and corrosion. The present work pertains to a study on wear resistance of surface coating of boron carbide on Ti–6Al–4V alloy using friction surfacing technique. Coating was formed by placing the boron carbide powder into the holes of predetermined depth on the surface and was characterized by metallography, electron probe micro analysis and dry sliding wear testing. The present study revealed that titanium alloy could be friction surfaced with boron carbide powder. The coating exhibited excellent wear resistance, which is attributed to the formation of strong metallurgical bond with the substrate. In the present work an attempt has also been made to compare the wear behaviour of surface composite layer on titanium alloy with that of conventionally used engineering materials such as mild steel and austenitic stainless steel. Wear data clearly revealed that wear resistance of friction stir surfaced composite layer is better than that of mild steel and stainless steel. This study demonstrated that friction stir surfacing is an effective strategy for the enhancement of wear resistance of titanium alloys.

Influence of Bio-Lubricants on the Tribological Properties of Ti6Al4V Alloy

Titanium alloy is one of the best materials for biomedical applications due to its superior biocompatibility, outstanding corrosion resistance, and low elastic modulus. However, the friction and wear behaviors of titanium alloys were sensitive to the environment including lubrication. In order to clarify the wear mechanism of titanium alloy under different lubrications including deionized water, physiological saline and bovine serum, the friction and wear tests were performed between Ti6Al4V plates and Si3N4 ball on a universal multi-functional tester. The friction and the wear rate of titanium alloy were measured under dry friction and three different lubrication conditions. The worn surfaces were examined by scanning electron microscopy. The results revealed that under the dry friction, the wear resistance of titanium alloy was the worst since the wear mechanism was mainly the combination of abrasive wear and oxidation wear. It was also found that Ti6Al4V alloy had low friction coefficient and wear rate under three lubrication conditions, and its wear mechanism was adhesive wear.

Phase constituents and microstructure of laser cladding Al 2O 3/Ti 3Al reinforced ceramic layer on titanium alloy

Laser cladding of the Fe 3Al + TiB 2/Al 2O 3 pre-placed alloy powder on Ti–6Al–4V alloy can form the Ti 3Al/Fe 3Al + TiB 2/Al 2O 3 ceramic layer, which can greatly increase wear resistance of titanium alloy. In this study, the Ti 3Al/Fe 3Al + TiB 2/Al 2O 3 ceramic layer has been researched by means of electron probe, X-ray diffraction, scanning electron microscope and micro-analyzer. In cladding process, Al 2O 3 can react with TiB 2 leading to formation of amount of Ti 3Al and B. This principle can be used to improve the Fe 3Al + TiB 2 laser cladded coating, it was found that with addition of Al 2O 3, the microstructure performance and micro-hardness of the coating was obviously improved due to the action of the Al–Ti–B system and hard phases.

Friction surfacing of titanium alloy with aluminium metal matrix composite

Present work pertains to investigation carried out on solid state surfacing of titanium alloy Ti–6Al–4V with AA2124SiCp metal matrix composite by friction surfacing. The coating was characterised by metallography and dry sliding wear. For the first time it was found that titanium alloy could be friction surfaced with metal matrix composites. The surface coating exhibited the wear properties to many‐fold than that of the titanium substrate. Significant improvement in the wear resistance of titanium alloy may be attributed to the interdiffusion of elements and the formation of nanocrystalline layer of the alloy at the interface.

High temperature friction and wear behaviour of sputter-deposited nanocrystalline (Mo xCr 1− x) 5Si 3 films by a double cathode glow discharge technique

In order to improve the wear resistance of titanium alloys, five kinds of sputter-deposited nanocrystalline (Mo x Cr 1− x ) 5Si 3( x = 1, 0.78, 0.75, 0.64, 0.57) films with average grain size 8 nm were fabricated on a substrate of Ti6Al4V alloy by means of a double cathode glow discharge technique. The microstructure and composition of the as-deposited films were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Nanoindentation was used to measure hardness ( H) and elastic modulus ( E) of the as-deposited films. High temperature friction and wear properties of the as-deposited films were investigated against ZrO 2 ceramic balls by a ball-on-disk system at 600 °C. Compared with the Ti6Al4V alloy, the friction coefficient values of the nanocrystalline (Mo x Cr 1− x ) 5Si 3 films were reduced by 0.2–0.3, and specific wear rates decreased by two orders of magnitude and were around or lower than 10 −6 mm 3/(N m) at the load ranging from 3.3 N to 4.8 N. The friction coefficient and specific wear rates of the as-deposited films relied on the Cr content in the nanocrystalline (Mo x Cr 1− x ) 5Si 3 films, and the higher the Cr content, the lower friction coefficient and wear rates.

Investigation of the Laser Melting Deposited TiAl Intermetallic Alloy on Titanium Alloy

To improve the wear resistance of Titanium alloy, TiAl intermetallic claddings were fabricated on TC4 substrate using laser melting deposition technology. Optical microscope, scan electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction meter were applied to investigate the deposited TiAl layer and their interface with substrate. Using hardness tester and M-2000 wear testing machine, hardness, frictional coefficient and wear resistance of the TiAl layers and TC4 alloy were tested. It was indicated that the deposited TiAl layers were well integrated with TC4 substrate, γ-TiAl and Ti3Al dual phase microstructure was formed in the deposited layer. With higher hardness and lower friction coefficient, the deposited TiAl layer improved the wear resistance obviously comparing to TC4 titanium alloy substrate.

Abrasive wear of ZrB2-containing spark-deposited and combined coatings on titanium alloy. I. microstructure and composition of ZrB2-containing coatings

To improve the abrasive wear resistance of titanium alloys, ZrB2-containing protective coatings are deposited by electrospark alloying (ESA). As electrode materials, composite ceramics with different amounts of ZrB2 are used. Some of the coated samples are also subjected to laser treatment to improve the coating by structuring the surface as alternating laser fusion tracks and nonfused sparkdeposited areas. The microstructure and phase composition of the coatings are characterized. The surface layer of the worn laser fusion tracks is found to have increased hardness (up to 22–38 GPa), which is two to four times higher than that of the surface before abrasion (~9.5 GPa).

Wear resistance of laser-deposited boride reinforced Ti-Nb–Zr–Ta alloy composites for orthopedic implants

The inherently poor wear resistance of titanium alloys limits their application as femoral heads in femoral (hip) implants. Reinforcing the soft matrix of titanium alloys (including new generation β-Ti alloys) with hard ceramic precipitates such as borides offers the possibility of substantially enhancing the wear resistance of these composites. The present study discusses the microstructure and wear resistance of laser-deposited boride reinforced composites based on Ti–Nb–Zr–Ta alloys. These composites have been deposited using the LENS™ process from a blend of elemental Ti, Nb, Zr, Ta, and boron powders and consist of complex borides dispersed in a matrix of β-Ti. The wear resistance of these composites has been compared with that of Ti–6Al–4V ELI, the current material of choice for orthopedic femoral implants, against two types of counterfaces, hard Si 3N 4 and softer SS440C stainless steel. Results suggest a substantial improvement in the wear resistance of the boride reinforced Ti–Nb–Zr–Ta alloys as compared with Ti–6Al–4V ELI against the softer counterface of SS440. The presence of an oxide layer on the surface of these alloys and composites also appears to have a substantial effect in terms of enhanced wear resistance.

In-Situ Synthesis of Metal Matrix Composite Coating with Laser Melting-Solidifying Processes

In order to improve wear resistance of titanium alloy, with pre-placed B4C and NiCrBSi powders on Ti-6Al-4V substrate, a process of laser melting-solidifying metal matrix composite coating was studied. The coating was examined using XRD, SEM and EDS. A good metal matrix composite coating was obtained in a proper laser process. There is a metallurgical interface bonding between the coating and the substrate. During laser melting-solidifying process, high energy of laser melted the pre-placed powders and a part of Ti-6Al-4V substrate, which made Ti extend into a melting pool. A reaction between Ti and B4C took place in the melting pool, which in-situ synthesized TiB2 and TiC reinforcements in the coating. The composite coating mainly consists of γ-Ni matrix, TiB2, TiC and CrB reinforcements. Microstructure of the reinforcements obtained using the laser melting-solidifying is not as same as that of reinforcements obtained using general producing methods. Due to high cooling rate of the melting pool, TiC nucleated primarily and grew up in dendrite morphology from undercooled liquid. Encircling TiC, TiB2 precipitated later and grew up in hexagonal prism morphology. TiC and TiB2 formed an inlaid microstructure.

Microstructural Investigation of Particulate Reinforced Ti-Sn Metal Matrix Composites

Titanium alloy is an attractive material for aerospace and automobile applications due to its lightweight and high strength. Titanium metal matrix composite (MMCs) is one of the promising materials which could be employed to enhance stiffness and wear resistance of titanium alloy. In this study, reinforcement of in-situ and ex-situ particulates has been investigated. The experimental results show that a dense microstructure with uniformly distributed in-situ TiB reinforcement phase in the Ti+B+Sn system could be obtained. It is present in either needle or blocky shape. This process involved warm pressing of mixed powder in semi-solid stage followed by sintering, which eliminated costly CIP and HIP processes. However, it is found that the ex-situ particulates in the titanium metal matrix are not suitable as reinforcements in Ti-Sn metal matrix as they either reacted with titanium during sintering process or generated a void at the interface between the reinforcement and the matrix.

Laser cladding NiCoCrAlY coating on Ti-6Al-4V

In order to improve wear resistance of titanium alloy, a process of laser cladding NiCoCrAlY coating on Ti-6Al-4V substrate with pre-placed NiCoCrAlY powder was studied. A good coating without cracks and pores was obtained in a proper laser process. The microstructure of the coating was examined using SEM and EDS. There is a metallurgical interface bonding between the coating and the substrate. The microstructure of Ni-base alloy coating is homogeneous austenite γ-Ni in cell and cell-dendrite morphology. The result of Vicker hardness tests that the average microhardness of the coating is HV800∼HV1000, and it is two times higher than that of Ti-6Al-4V substrate.

Laser Cladding Ni-Base Composite Coating on Titanium Alloy with Pre-Placed B4C+NiCoCrAlY

Using a CO2 laser, a process of cladding Ni-base composite coating on Ti6Al4V with pre-placed B4C and NiCoCrAlY was studied. A good metallurgical bonding coating without cracks and pores was obtained in reasonable ratios of components and low energy laser process. Morphology and microstructure of the coating were analyzed with OM, XRD, SEM and EDS. It is certain that there was a reaction between B4C and Ti during in-situ producing TiB2 and TiC. The Ni-base composite coating is strengthened with TiB2 and TiC reinforcement phases. Vickers Hardness Tester measured that the average microhardness of the coating is HV1200 and it is 3.5 times of the Ti6Al4V substrate. The high hard coating containing several reinforcement phases greatly enhances wear resistance of titanium alloy.