Titanium Alloys For Biomedical Applications Research Articles

Gallium-Containing Materials and Their Potential within New-Generation Titanium Alloys for Biomedical Applications.

With the rising demand for implantable orthopaedic medical devices and the dominance of device-associated infections, extensive research into the development of novel materials has been prompted. Among these, new-generation titanium alloys with biocompatible elements and improved stiffness levels have received much attention. Furthermore, the development of titanium-based materials that can impart antibacterial function has demonstrated promising results, where gallium has exhibited superior antimicrobial action. This has been evidenced by the addition of gallium to various biomaterials including titanium alloys. Therefore, this paper aims to review the antibacterial activity of gallium when incorporated into biomedical materials, with a focus on titanium-based alloys. First, discussion into the development of new-generation Ti alloys that possess biocompatible elements and reduced Young's moduli is presented. This includes a brief review of the influence of alloying elements, processing techniques and the resulting biocompatibilities of the materials found in the literature. The antibacterial effect of gallium added to various materials, including bioglasses, liquid metals, and bioceramics, is then reviewed and discussed. Finally, a key focus is given to the incorporation of gallium into titanium systems for which the inherent mechanical, biocompatible, and antibacterial effects are reviewed and discussed in more detail, leading to suggestions and directions for further research in this area.

Processing of the Ti25Ta25Nb3Sn Experimental Alloy Using ECAP Process for Biomedical Applications

The development of titanium-β alloys for biomedical applications is associated with the addition of alloying elements or the use of processing techniques to obtain suitable bulk properties. The Ti25Ta25Nb3Sn alloy has been highlighted for its mechanical properties and biocompatibility. To further enhance the properties of titanium alloys for biomedical applications, equal channel angular pressing (ECAP) was used due to its capability of refining the microstructure of the alloy, leading to improved mechanical properties without significant changes in Young’s modulus. This study aims to evaluate the impact of ECAP on the microstructure of the Ti-25Sn-25Nb-3Nb alloy and investigate the correlation between the microstructure, mechanical properties, and corrosive behavior. Grain refinement was achieved after four ECAP passes, with an average grain diameter of 395 nm and a non-homogeneous structure, and microhardness was slightly increased from 193 to 212 HV after four ECAP passes. The thermomechanical aspects of the ECAP processing have led to the formation of a metastable α″ phase during the first two passes, while after four passes, the structure was composed only of the β phase. The corrosion resistance of the alloy was increased after four passes, presenting the best results in terms of the improvement of passivation corrosion density.

Electrochemical anodization of cast titanium alloys in oxalic acid for biomedical applications

Titanium and its alloys have numerous biomedical applications thanks to the composition and morphology of their oxide film. In this study, the colorful oxide films were formed by anodizing cast Ti-6Al-4V and Ti-6Al-7Nb alloys in a 10% oxalic acid solution for 30 s at different voltages (20–80 V) of a direct current power supply. Atomic force microscopy was used as an accurate tool to measure the surface roughness of thin films on the nanometer scale. Scanning electron microscopy and X-ray diffraction were performed to analyze surface morphology and phase structure. According to the results, the produced titanium oxide layer showed high surface roughness, which increased with increasing anodizing voltage. The impact of anodizing voltages on the color and roughness of anodized layers was surveyed. The corrosion resistance of the anodized samples was studied in simulated body fluid at pH 7.4 and a temperature of 37 °C utilizing electrochemical impedance spectroscopy and the potentiodynamic polarization method. The anodized samples for both alloys at 40 V were at the optimal voltage, leading to a TiO2 layer formation with the best compromise between oxide thickness and corrosion resistance. Also, findings showed that TiO2 films produced on Ti-6Al-7Nb alloys had superior surface roughness properties compared to those of Ti-6Al-4V alloys, making them more appropriate for orthopedic applications. From the obtained data and the fruitful discussion, it was found that the utilized procedure is simple, low-cost, and repeatable. Therefore, anodization in 10% oxalic acid proved a viable alternative for the surface finishing of titanium alloys for biomedical applications.

Hybrid Polymer–Inorganic Coatings Enriched with Carbon Nanotubes on Ti-6Al-4V Alloy for Biomedical Applications

Bone tissue degeneration, caused by disease as well as trauma, is a problem affecting many social groups in the 21st century. It involves pain and reduced patient comfort. Developments in materials engineering allow for the design of novel, innovative materials that can be used in therapies to promote bone regeneration. This work presents the preparation of a ceramic–polymer coating modified with carbon nanotubes on a titanium alloy for biomedical applications. The ceramic part is hydroxyapatite synthesized by the wet precipitation method using orthophosphate and calcium hydroxide. The polymer of choice was polyethylene glycol. A UV light synthesis method was successfully applied to obtain coatings characterized by continuity and full crosslinking. Extensive physicochemical analysis and incubation studies were carried out. Interactions between coatings and fluids mimicking artificial biological environments were analyzed for 9 days, i.e., in fluids such as SBF solution, artificial saliva, and distilled water. During the in vitro incubation, changes in pH values were measured by potentiometric tests, and ionic conductivity was measured by analyzing conductometry. After incubation, the surface morphology was studied by scanning electron microscopy (SEM) together with energy-dispersive (EDS) microanalysis, which made it possible to determine the presence of individual elements on the surface, as well as to observe the appearance of new apatite layers. Fourier-transform infrared (FT-IR) spectrometry was also performed before and at the end of the incubation period. On the basis of the presented studies, it was concluded that coatings that contain nanotubes are bioactive and do not negatively affect the properties of the coatings. Bioactivity was confirmed microscopically by observing new apatite layers after incubation in SBF, which were identified as phosphorus and calcium deposits. Degradation of the polymer phase was observed in the artificial saliva. These materials require further study, including safety analysis, but they demonstrate potential for further work.

COMPARISON AND PERFORMANCE OF α, α+β AND β TITANIUM ALLOYS FOR BIOMEDICAL APPLICATIONS

As implant materials, titanium and its alloys have been extensively utilized because of their exceptional mechanical properties and biocompatibility. Despite this, corporations and researchers alike have kept up their aggressive pursuit of better alloys since there are still issues that require immediate attention. One of these causes a problem with stress shielding as a noticeable variation in the elastic modulus of the implant material. Ti alloys release harmful ions after extended usage. The poor bioactivity of the Ti alloy surface slows the healing process. In order to address these problems, additional research has concentrated on developing Ti alloys for the 21st century that contain a more suitable phase and change the surface of the alloy from inherently bioinert to bioactive. This study assesses the knowledge presently existing on the biological, chemical, mechanical, and electrochemical characteristics of important [Formula: see text]-Ti alloys created in recent years with the objective to provide scientific justification for using [Formula: see text]-titanium-based alloys as a substitute for cpTi. Dental implants might be made using [Formula: see text]-Ti alloys as an alternative. The enhanced alloy qualities, which include a lower modulus of elasticity, improved strength, suitable biocompatibility, and good abrasion and excellent resistance to corrosion, offer the essential proof. Additionally, structural, chemical, and thermomechanical modifications to [Formula: see text]-Ti alloys allow for the production of materials that may be tailored to the needs of unique instances for clinical practises. By researching the paper, the performance and attributes of [Formula: see text]-titanium alloy are compared to those of other forms of titanium alloy, such as [Formula: see text] titanium alloys. To support their usage as cpTi substitutes, in vivo studies are required to assess new [Formula: see text]-titanium alloys.

Micro-abrasive wear behavior by ball cratering on MAO coating of Ti–25Ta alloy

Surface treatments are widely used techniques to improve the wear resistance of titanium alloys for biomedical applications. Modification by micro-arc oxidation (MAO) creates an oxide ceramic coating of alloy substrate to improve wear resistance. This work investigated the micro-abrasive wear by ball cratering of MAO coatings over Ti–25Ta alloy. For this purpose, the surfaces were worn by steel balls at a load of 2 N and a rotation speed of 200 rpm. After 50 min of testing, the depth of the wear reaches the substrate, confirming that the MAO coating has a much lower wear rate. Guided by Archard's law, the wear volume, wear rate, and MAO coating thickness were calculated through wear test.

Artificial implants of titanium alloys for biomedical applications

The evolving healthcare industry, driven by the growing need for joint replacement surgeries, musculoskeletal repairs, and orthodontic procedures on a global scale, has prompted the creation of innovative technologies. These emerging technologies are designed to adapt to evolving healthcare needs. In the field of biomedicine, there is a history of using metallic orthopedic materials alongside aerospace industry applications. While these materials are only partially effective in the biomedical domain, they are still considered suitable for bone tissue replacements and regenerative therapies because of their exceptional mechanical properties. Tantalum and Molybdenum elements were added to the titanium to improve the corrosion resistance and mechanical properties because Tantalum and Molybdenum are considered β-stabilizer elements. This research focused on synthesizing the Ti-10Mo-20Ta alloy using arc-melting, placing particular importance on its potential medical applications. Furthermore, the investigation scrutinized the consequences of subjecting the alloy to hot annealing at a temperature of 1050 ºC for a duration of 1.5 hours. Subsequently, the alloy was rapidly immersed in water, and its microstructure and mechanical properties were analyzed. The alloy was characterized utilizing methods like X-ray diffraction and optical microscopy, and transmission electron microscopy. The results obtained indicated that the material possessed a metastable β structure with minimal α phase presence, as revealed through structural analysis. Tensile strength testing conducted at room temperature exhibited a significantly higher value of around 1200 MPa in comparison to Ti-6Al-4V and CP-Ti alloys. These alloys were deemed suitable for their intended purpose as orthopaedic implants.

Experimental Research on New Developed Titanium Alloys for Biomedical Applications

The mechanical properties and electrochemical behavior of two new titanium alloys, Ti20Mo7Zr and Ti20Mo7Zr0.5Si, are investigated in this paper. The alloys have been manufactured by vacuum arc remelting (VAR) technique and studied to determine their microstructure, corrosion behavior, and mechanical properties. Metallographic observations and quantitative microanalysis by optical microscopy, scanning electron microscopy SEM, and energy dispersive X-rays spectroscopy EDX were performed. Data about the three-point bending test and microhardness are presented. For electrochemical properties, three different environments were used: Ringer solution at 25 °C, Ringer solution at 40 °C simulating fever condition, and 3.5% NaCl solution. Metallographic investigation revealed the biphasic and dendritic structure of both samples when the procedures were performed. Electrochemical testing in body simulation fluid, fever conditions, and saline medium showed that the lower the proportion of silicon in the samples, the higher the corrosion resistance. The formation of a titanium oxide layer on the surface of both samples was noticed using quantitative EDX analysis. The three-point bending test for the two samples revealed that the presence of silicon decreases the modulus of elasticity; the surface of the samples displayed soft and hard phases in the microhardness test. Electrochemical impedance spectroscopy (EIS) measurements were carried out at different potentials, and the obtained spectra exhibit a two-time constant system, attesting double-layer passive film on the samples.

Development and Investigation of Mesoporous Bioactive Glass/Zein Coatings Electrodeposited on Titanium Alloy for Biomedical Applications

The objective of the present work was the development of cathodic electrophoretic deposition (EPD) to obtain composite coatings of mesoporous sol–gel glass (MSGG) particles embedded in a zein matrix on Ti-13Nb-13Zr substrates. To deposit robust and repeatable coatings, a direct current EPD and pulsed direct current EPD as well as the deposition kinetics were investigated, including the deposition yield and deposition rate. The stability of the suspension was determined based on the zeta potential and conductivity. Macroscopically homogeneous coatings with a thickness of about 10 µm and various volume fractions of MSGG were subjected to further examination. Coatings were uniform, exhibiting open porosity and showing excellent adhesion to the substrates. Both zein and MSGG particles revealed an amorphous structure. The coated substrates demonstrated greater resistance to electrochemical corrosion in Ringer's electrolyte in comparison with the virgin (non-coated) substrate. The coatings showed high roughness and moderate hydrophilicity. The incubation of the coated substrates in concentrated 1.5 simulated body fluid (1.5SBF) showed the formation of carbonate hydroxyapatite. The composite coatings showed improved antibacterial properties against gram-negative E. coli and gram-positive S. aureus bacteria compared to pure zein coatings. Electrophoretic MSGG/zein composite coatings should be further investigated in terms of their osteoconductive behavior, to confirm their suitability for medical applications in orthopedics.

Titanium alloy selection for biomedical application using weighted sum model methodology

To manufacture physical object some kinds of materials are required. Many times, lot of materials are available that satisfy the objective, in such cases material selection become very important. Material selection is however, thought-provoking and monotonous this is because of the complex connection between various conflicting decision criteria for choosing alternating material. Generally, the main objectives for material selection are cost and improvement in performance, however criteria like weight reduction, biocompatibility improvement, failure, corrosion performance are also inspirations for legitimate material choice. For instance, in the aviation industry weight reduction is main focus. If improper material used for any application, then it might lead to manufacturer and customer unsatisfaction. It can likewise lead to assembly failure as well as badly effects performance of a product, consequently productivity and profitability influenced badly and damage organization reputation. To take care of the issue of material selection, distinctive strategy has been utilized and one of the well-known techniques that have been applied is the Weighted Sum Model technique for the titanium and their alloys utilized in biomedical usage. It was observed that weighted sum model can be used to identify the ideally best Titanium alloy for biomedical applications. As a result of the findings, it has been determined that Ti-35.3Nb-7.1Zr-5.1Ta material is greatest all-rounder for biological applications. It was observed that the developed methodology can be applied to various different applications in along with material selection.

Microstructure evolution and corrosion behaviour of a high Mo containing α + β titanium alloy for biomedical applications

In the present work, effect of heat treatment on microstructure and corrosion behaviour of a high Mo containing α + β titanium alloy (Ti-6Al-1 V-4Mo-0.1Si) has been investigated. Heat treatment results in the formation of wide variety of microstructure depending on the heating temperature (below or above the β transus) and cooling conditions. Martensite was observed after oil quenching (OQ), Widmanstatten α (αWS) + β after air cooling (AC) and lamellar α (αL) + β after furnace cooling (FC). The corrosion behaviour of the heat-treated specimens were studied in simulated body fluid (SBF) at 37 °C using open circuit potential-time (OCP), electrochemical impedance spectroscopy (EIS) and potentio-dynamic polarization tests. X-ray photoelectron spectroscopy (XPS) was used to investigate the chemical nature of the corroded surfaces. The study revealed that, in general, OQed samples had increased corrosion resistance than the ACed and FCed samples. XPS confirmed the presence of TiO2 and Al2O3 on the corroded sample. The alloy's improved corrosion resistance was attributed to stable inert TiO2 film. Samples heat treated at 950 °C were found to have better corrosion resistance in general.

Corrosion and wear performances of hydroxyapatite and boron-containing TiO2 composite coatings on Ti6Al7Nb alloy

Plasma electrolytic oxidation coupled with hydrothermal treatment is a relatively new technique to form a hydroxyapatite/TiO2 layer on titanium alloys for biomedical applications. Hence the process allows achieving a bioactive and bactericidal surface by using electrolytes that contain ions (such as calcium-phosphorus and boron) necessary for desired properties. The coating properties are controllable by adjusting the parameters in the PEO process. In the present study, an electrolyte that contains both calcium, phosphorus, and boron ions was used to form a rough and porous oxide layer on Ti6Al7Nb which is known to be less toxic than the most widely used Ti alloy for biomedical applications, Ti6Al4V. A hydroxyapatite and boron-containing oxide layer was obtained after plasma electrolytic oxidation and hydrothermal treatment. Coatings were examined by XRD, XPS, SEM, contact angle measurement system, micro-hardness tester, wear tester, and corrosion measurement system. The results showed that the wear and the corrosion properties of all coated samples increased. Especially boron doping enhanced both the wear and corrosion resistance. Relatively the best corrosion resistance was achieved from CaP-B and the best wear resistance was from HA-B samples. The hardness values and mean surface roughness of all coated samples also increased while the average friction coefficients decreased. The hardness increased from 323 ± 5 HV0.1 to 1084 ± 16 HV0.1 where the coefficient of friction decreased from 0.5672 ± 0.01 to 0.4697 ± 0.03.

Fabrication of a β-based titanium alloy for biomedical applications

The aim of this study was to produce a titanium-based alloy with mainly β-phase and reduced Young’s modulus for biomedical applications. Alloys Ti-Nbx-Ta5-Zrx5 (x = 20, 30, 40 at.%Nb) were prepared by arc melting then solution annealed at 950℃ for 1 h, and aged at 480℃ for 12 h. Optical microscopy showed mixtures of dendritic and needle-like microstructures before and after heat treatment in all alloys. X-ray diffraction (XRD) identified β-phase in all alloys. Small fractions of orthorhombic martensite (αʹ) and ω-phase were also detected by XRD which decreased after ageing. Alloy Ti-Nb20-Ta5-Zr5 had the lowest Young’s modulus, derived from nanoindentation hardness of 69.8 ± 7.2 GPa in the as cast condition. There was no significant change in elastic modulus of the alloy after ageing (70.8 ± 6.8 GPa). As-cast Ti-Nb30-Ta5-Zr5 had the highest elastic modulus of 94.7 ± 3.0 GPa. The elastic modulus decreased to 84.4 ± 0.32 GPa after heat treatment.

Modern methods of surface modification for new-generation titanium alloys

The constantly growing need for the use of implants in osteotomy is mainly due to the aging population and the need for long-term use of this type of biomaterials. Improving implant materials requires the selection of appropriate functional properties. Currently used titanium (Ti) alloys, such as Ti6Al4V and Ti6Al7Nb, are being replaced by materials with better biocompatibility, such as vanadium (V) or niobium (Nb), allowing for creation of the so-called new generation alloys. These new alloys, with the incorporation of zirconium (Zr), iron, and tantalum, possess Young’s modulus close to that of a bone, which further improves the improves the biomaterial’s. biocompatibility. This article describes the atomic layer deposition (ALD) method and its possible applications in the new generation of titanium alloys for biomedical applications. Also, the exemplary results of tin oxide (SnO2) thin coatings deposited by ALD and physical vapor deposition (PVD) methods are presented. This study aimed to evaluate the physicochemical properties of a Ti13Nb13Zr alloy used for elements in the skeletal system. As the temperature and the number of cycles vary, the results demonstrate that the surface area of the samples changes. The uncoated Ti13Nb13Zr alloy exhibits hydrophilic properties. However, all coated specimens improve in this respect and provide improved clinical results. after the applied modification, the samples have a smaller contact angle, but still remain in the range of 0–90°, which makes it possible to conclude that their nature remains hydrophilic. Coating the specimens decreased the mineralization risk of postoperative complications. As a result, the biomaterials demonstrated improved effectiveness, decreased complication indicators, and improved patient well-being

Microstructure and tensile properties of heat-treated Ti-Mo alloys

Current research is focused on development of β-type titanium alloys for biomedical applications as substitutes of the undesirable Ti6Al4V alloy. Ti6Al4V alloy has a higher elastic modulus (110 GPa) than that of the human bone (10-30 GPa) and this mismatch in elastic moduli can cause stress shielding effect, which can cause bone resorption and implant failure. Moreover, the dissociation of vanadium and aluminium can cause long term diseases including Alzheimer, neuropathy. β-type titanium alloys are potential substitute materials due to their good biocompatibility and the β phase has a lower elastic modulus. The aim was to study the microstructure and tensile properties of heat-treated Ti-xMo alloys (x= 8 & 10wt%). Phase analysis was conducted using X-ray diffractometer, while the microstructure was observed using an optical microscope. The tensile properties were examined using a tensile test machine. Acicular structures of α" phase precipitated in the β matrix in Ti-8Mo alloy, while Ti-10Mo alloy showed predominant β phase. The theoretically predicted phase constituents were not consistent with the experimental findings. Ti-10Mo alloy possessed superior yield and tensile strengths, larger elongation, and lower elastic moduli than that of Ti6Al4V alloy. Based on the obtained findings, the Ti-10Mo alloy can be a potential candidate for orthopaedic application. acicular structures of α" phase.

A novel low-modulus titanium alloy for biomedical applications: A comparison between selective laser melting and metal injection moulding

The mechanical properties of new low-modulus beta titanium alloyed designed for biomedical applications are measured and compared when processed via the selective laser melting (SLM) and the metal injection moulding (MIM) processes. Mechanical tensile testing reveals important differences between them: (i) Under optimal laser settings, SLM produces strong, low-modulus and ductile properties. This is associated with the laser creating fully dense material with appropriate microstructure after solidification. (ii) MIM can produce materials with similar strength/stiffness ratios, but with reduced ductility. The differences between the processes are linked to changes in chemistry in the microstructure: carbon pickup from MIM binder and slow cooling rate is responsible for the appearance of Ti2C resulting in low ductility and very high strength together with a transition from intergranular to transgranular fracture.

Machine learning-guided design and development of metallic structural materials

In recent years, the advent of machine learning (ML) in materials science has provided a new tool for accelerating the design and discovery of new materials with a superior combination of mechanical properties for structural applications. In this review, we provide a brief overview of the current status of the ML-aided design and development of metallic alloys for structural applications, including high-performance copper alloys, nickel- and cobalt-based superalloys, titanium alloys for biomedical applications and high strength steel. We also present our perspectives regarding the further acceleration of data-driven discovery, development, design and deployment of metallic structural materials and the adoption of ML-based techniques in this endeavor.

Biocompatibility, corrosion, and wear resistance of β titanium alloys for biomedical applications

A novel β– Ti-xNb-3.5Sn alloys (x = 33, 36, and 39 wt. % Nb) were made using mechanical alloying of elemental powders by cold isostatic pressing. These powders were blended and then milled at different times using a planetary ball mill. The milled powders were compacted and then consolidated at different temperatures. The produced alloys were characterized as a biomedical material; using a scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) analysis, corrosion, wear resistance, as well as biocompatibility. The results showed that the titanium was completely transformed from (α to (the phase after milling time of 4 h and consolidation temperature of 1000 °C. Good results for both wear resistance, biocompatibility and corrosion resistance came from the addition of niobium. Biocompatibility slightly decreases with increasing the milling time and decreasing the consolidation temperature. This is due to the presence of FeO phase that is coming from ball contamination during the milling process. The wear resistance decreases with increasing both the milling time and consolidation temperature. The good corrosion resistance and adequate wear resistance, further that the investigated alloy is an attractive material for an orthopedic implant.

Recent Development in Beta Titanium Alloys for Biomedical Applications

β-type titanium (Ti) alloys have attracted a lot of attention as novel biomedical materials in the past decades due to their low elastic moduli and good biocompatibility. This article provides a broad and extensive review of β-type Ti alloys in terms of alloy design, preparation methods, mechanical properties, corrosion behavior, and biocompatibility. After briefly introducing the development of Ti and Ti alloys for biomedical applications, this article reviews the design of β-type Ti alloys from the perspective of the molybdenum equivalency (Moeq) method and DV-Xα molecular orbital method. Based on these methods, a considerable number of β-type Ti alloys are developed. Although β-type Ti alloys have lower elastic moduli compared with other types of Ti alloys, they still possess higher elastic moduli than human bones. Therefore, porous β-type Ti alloys with declined elastic modulus have been developed by some preparation methods, such as powder metallurgy, additive manufacture and so on. As reviewed, β-type Ti alloys have comparable or even better mechanical properties, corrosion behavior, and biocompatibility compared with other types of Ti alloys. Hence, β-type Ti alloys are the more suitable materials used as implant materials. However, there are still some problems with β-type Ti alloys, such as biological inertness. As such, summarizing the findings from the current literature, suggestions forβ-type Ti alloys with bioactive coatings are proposed for the future development.

Influence of lubricating conditions on the two-body wear behavior and hardness of titanium alloys for biomedical applications

Commercially pure titanium and titanium alloys are often preferred in biomedical applications due to their high biocompatibility behavior. However, the inadequate wear, fatigue and corrosion resistance of titanium alloys limit their use as a biomaterial in the human body. Furthermore, these alloys may contain such as aluminum and vanadium elements that can damage the nervous system. The aim of this in vitro study was to evaluate the influence of lubrication conditions on the two-body wear behavior of pure titanium, Ti-2.5Si-5Zr, Ti-5Si-5Zr, and Ti-6Al-4V using dual-axis computer-controlled wear simulator device. The mean wear volume loss of all test specimens after the two-body wear test procedures were determined to use a non-contact 3D profilometer. The alloys hardness and microstructures were evaluated using the Vickers indention method, scanning electron microscopy (SEM), X-ray spectroscopy (EDS), and X-ray diffraction (XRD) analysis. The hardness of Ti-6Al-4V titanium alloy material was significantly greater than the other alloy materials and cp-Ti. The mean wear volume loss of Ti-5Si-5Zr test specimens was lower than the other test group specimens irrespective of lubrication conditions. It was concluded, the two-body wear resistance of the alloy formed with the addition of silica to the pure titanium is increased after both wear test procedures. However, for the test materials in this study considered, correlations between the two-body wear resistance and hardness were found to be insignificant.