Surface Roughness Of Specimens Research Articles

Effect of slide burnishing of shoulder fillets on the fatigue strength of X19NiCrMo4 steel shafts

The article presents the results of investigations on the influence of the technological parameters of slide burnishing of shoulder fillets on a shaft on the fatigue strength of machine components. Fatigue tests were carried out for shafts made of X19NiCrMo4 steel after the electroslag remelting process. The burnishing process of the shoulder fillets of shafts were carried out with tools characterized by different values of tip radius and at varying angles of tool slope in relation to normal with regard to the generating line of the shaft journal. The burnishing improved fatigue strength by 28.5% compared to the non-burnished specimens. Compared with turning, the surface roughness of specimens subjected to slide burnishing decreased in the range from 64.1% to 85.8%. The measurements of the microhardness of the surface layer showed that through slide burnishing, it is possible to strengthen the surface layer by 32% down to a depth of up to 0.018 mm compared to the core hardness.

Properties of the Surface Layer After Trochoidal Milling and Brushing: Experimental Study and Artificial Neural Network Simulation

The aim of this study was to investigate the effect of milling and brushing cutting data settings on the surface geometry and energy parameters of two Mg alloy substrates: AZ91D and AZ31. In milling, the cutting speed and the trochoidal step were modified (vc = 400–1200 m/min and str = 5–30%) to investigate how they affect selected 2D (Rz, Rku, Rsk, RSm, Ra) and 3D (Sa, Sz, Sku, Ssk) roughness parameters. The brushing treatment was carried out at constant parameters: n = 5000 rev/min, vf = 300 mm/min, ap = 0.5 mm. The surface roughness of specimens was assessed with the Ra, Rz, and RSm parameters. The effects of the two treatments on the workpiece surface were analyzed comparatively. It was found that the roughness properties of the machined surface may be improved by the application of a carbide milling cutter and ceramic brush. The use of different machining data was also shown to impact the surface free energy and its polar component of Mg alloy specimens. Complementary to the results from the experimental part of the study, the investigated machining processes were modelled by means of statistical artificial neural networks (the radial basis function and multi-layered perceptron). The artificial neural networks (ANNs) were shown to perform well as a tool for the prediction of Mg alloy surface roughness parameters and the maximum height of the profile (Rz) after milling and brushing.

Effect of Post Treatment on the Microstructure, Surface Roughness and Residual Stress Regarding the Fatigue Strength of Selectively Laser Melted AlSi10Mg Structures

This paper focusses on the effect of hot isostatic pressing (HIP) and a solution annealing post treatment on the fatigue strength of selectively laser melted (SLM) AlSi10Mg structures. The aim of this work is to assess the effect of the unprocessed (as-built) surface and residual stresses, regarding the fatigue behaviour for each condition. The surface roughness of unprocessed specimens is evaluated based on digital light optical microscopy and subsequent three-dimensional image post processing. To holistically characterize contributing factors to the fatigue strength, the axial surface residual stress of all specimens with unprocessed surfaces is measured using X-ray diffraction. Furthermore, the in-depth residual stress distribution of selected samples is analyzed. The fatigue strength is evaluated by tension-compression high-cycle fatigue tests under a load stress ratio of R = −1. For the machined specimens, intrinsic defects like pores or intermetallic phases are identified as the failure origin. Regarding the unprocessed test series, surface features cause the failures that correspond to significantly reduced cyclic material properties of approximately −60% referring to machined ones. There are beneficial effects on the surface roughness and residual stresses evoked due to the post treatments. Considering the aforementioned influencing factors, this study provides a fatigue assessment of the mentioned conditions of the investigated Al-material.

Predictive analysis of surface roughness in EDM using semi-empirical, ANN and ANFIS techniques: A comparative study

This paper investigates the application of assisted electrical discharge machining (AAEDM) of D3 steel. Compressed argon gas in traditional EDM under controllable parameters was utilized to access the surface roughness (SR) of machined specimens. In this research work, a mathematical model was actuated to realize the SR by utilizing dimensional analysis hypothesis. The experimental and foreseen assessments of SR during the procedure, acquired by Buckingham pie-theorem, ANN and ANFIS, were observed to be as per one another. Be that as it may, the ANFIS strategy demonstrated to be all the more fitting to the EDM output when contrasted with the ANN and the semi-empirical model.

Determination of the influence of a stress-relief heat treatment and additively manufactured surface on the fatigue behavior of selectively laser melted AISI 316L by using efficient short-time procedures

To use Additive Manufacturing (AM) technology for production of safety critical structural components, it is indispensable to investigate thoroughly the materials AM specific microstructure as well as the resulting mechanical and especially cyclic properties. Besides their special microstructure, AM materials show a highly inhomogeneous distribution of residual stresses as well as numerous process induced microstructural notches, e.g. pores in the materials volume and high roughness of additively manufactured surfaces. Therefore, in production of AM components stress-relief heat treatments as well as surface post-processing are commonly used. In the present work, the influence of stress-relief heat treatment as well as the additively manufactured surface condition on the cyclic properties was investigated at selectively laser melted (SLM) specimens made of AISI 316L stainless steel. Specimens were manufactured in horizontal as well as vertical building direction, leading to layer planes oriented parallel and perpendicular to the loading direction, respectively. To reduce the high material and time effort in fatigue investigations, the short-time methods PhyBaLCHT, which is based on cyclic indentation tests and enables a characterization of the materials defect tolerance, as well as load increase tests (LITs) were used for qualitative analyzes of the cyclic deformation behavior. Moreover, the physically based lifetime calculation approach (PhyBaLLIT) was applied for quantitative determination of the fatigue behavior of heat treated specimens, showing excellent correlation to additional constant amplitude tests (CATs), performed for validation. While the heat treatment does not significantly influence the fatigue behavior of vertically built specimens, an increase of fatigue strength could be observed for horizontal building direction, which is mainly caused by an improved defect tolerance. The higher defect tolerance was determined with PhyBaLCHT and could be proved by fracture mechanics considerations using the area-concept. Furthermore, the results show a significantly lower fatigue lifetime for additively manufactured surface condition compared with polished samples, which is more pronounced for vertically built specimens, because of the higher surface roughness of specimens manufactured in this building direction. Moreover, a double-staged S-Nf curve could be observed for specimens with additively manufactured surface, which correlates to the cyclic deformation behavior observed in LITs and CATs.

Particle characterisation of rail sands for understanding tribological behaviour

Low adhesion between a train’s wheel and the rail can cause performance and safety issues, costing the UK rail industry ~£345 m/annum. Sand is applied to the wheel/rail interface to increase traction when low adhesion conditions are present. In order to improve performance, an understanding of how particles are entrained into and act within the interface is needed. This paper outlines a particle characterisation framework and applies it to sands used in the rail industry: Leighton Buzzard (LB), Central European (CE), and Derbyshire Youlgreave (DY) sand. The largest difference found in this framework was between the sand’s particle size, LB being largest, then CE, then DY. A high pressure torsion rig measured traction when the sands were applied to dry, wet, and leaf extract contaminated conditions, the latter two representing low adhesion conditions. All sands had no impact on wheel/rail adhesion in dry conditions; in low adhesion conditions DY had little influence, whereas LB and CE were found to increase traction. Particles in dry conditions had no effect on test specimen surface roughness, whereas roughness increased when sand was applied in low adhesion conditions. The developed characterisation framework provides a platform for assessing prospective adhesion enhancing particles.

Preparation, morphological, and mechanical characterization of titanium dioxide (TiO2)/polyvinyl alcohol (PVA) composite for gamma-rays radiation shielding

Polyvinyl alcohol (PVA) has been prepared as a films with different volume ratios of titanium dioxide (TiO2). Atomic force microscope (AFM) was used to test morphology and grain size of the specimen surfaces. The results revealed that the surface roughness of specimen decreased with increasing the ratio of TiO2 whereas the grain size was increased. The stress-strain curves for TiO2/PVA composite films with 0%, 0.02%, 0.03%, and 0.04% TiO2 content are characterized. The mechanical performance of the TiO2/PVA composite films was clearly affected according to loaded TiO2 contrast to that of the pure film. Furthermore, the titanium dioxide (TiO2)/polyvinyl alcohol (PVA) composite samples examined as a shielding material of gamma ray. linear attenuation coefficient was measured by using the Cesium-137 (Cs-137) and gamma-ray photons 662 keV as a radioactive source. It was shown that the efficiency of shielding material increased with increasing the loaded amount of TiO2.

Effect of surface mechanical attrition treatment on corrosion fatigue behavior of AZ31B magnesium alloy

Surface mechanical attrition treatment (SMAT) is considered as an effective technology to influence fatigue and corrosion resistance as these properties are largely related to surface structure and property. Despite the increasing number of studies that report the effects of SMAT on separate fatigue or corrosion behaviors, the impact of SMAT on fatigue property under corrosive environment is left unexplored. In this paper, the corrosion fatigue properties of AZ31B magnesium alloy before and after SMAT process are investigated. Hydrogen evolution tests and potentiodynamic polarization tests are carried out to obtain the corrosion resistance, and it is found that SMAT promotes corrosion rate. The surface roughness of SMATed specimen also increases, which accelerates corrosion rate. In terms of fatigue properties, the fatigue life of SMATed specimen is found to be higher, in both air and 3% NaCl solution. And the larger the size of stainless steel balls used during processing SMAT specimens, the longer the fatigue life. Under 3% NaCl corrosive environment, the beneficial effects induced by SMAT process gradually emerge with increasing stress amplitude during fatigue tests. Reduced fatigue life of SMATed specimen under corrosive environment is attributed to roughened interface between deformed surface layer and bulk material. Nevertheless, the crack initiation sites for SMAT specimens are the same in both air and NaCl solution, all located at the subsurface area.

Tribological Properties of Cyperus Pangorei Fibre Reinforced Polyester Composites(Friction and Wear Behaviour of Cyperus Pangorei Fibre/Polyester Composites)

ABSTRACT This paper investigated the tribological behavior of natural fiber-reinforced polyester composites. The Cyperus pangorei (CP) fiber and polyester were used as a reinforcement material and thermosetting matrix, respectively. The composites were fabricated using compression molding technique with 40 wt% of CP fiber. Technological properties such as density, hardness, and wear of the composite specimens were determined. The density and shore D hardness of the prepared specimens were 1.0176 g/cc ± 0.106 and 87.25 ± 4.1, respectively. A pin-on-disk wear test machine was used to conduct the dry sliding wear test with constant sliding distance; various sliding velocities of 1, 2, and 3 m/s; and a range of contact pressure of 0.13–0.38 MPa. After the wear test, the surface roughness of worn specimens was measured. The specific wear rate increased when the applied load was increased on the specimen. A non-linear decrease in coefficient of friction was observed with the combination of increasing contact pressure and decreasing sliding velocity. The morphological analyses were carried out using a scanning electron microscope for the worn specimens.

Evaluation the Effect of Fibers Addition on Mechanical Properties of Flexible Acrylic Resin

Background: In chemistry the development of polymer has produced another material to poly methyl methacrylate such as epoxy resins, polyamides (nylon), acetyl resins -----etc. All these resins are suited for thermoplastic processing. Polyamide materials are more flexible than the commonly used polymethylmethacrylate. The flexibility of polyamide allows partial dentures to be pressed in one piece including clasps. Glass fibers are the most widely used reinforcing materials forming about 90 % of the reinforcement in resins. The addition of fibers to provisional restorative resin increases tensile strength, fracture toughness and surface hardness. Objective of the study: An evaluation of the surface roughness, modulus of elasticity and tensile strength improvement of flexible denture bases after adding of glass fibers and altering in powder – monomer ratio. Material and Methods: Eighty samples of flexible acrylic were made and divided into two main groups according to the type of test to be used. Forty samples for surface roughness and forty samples for tensile strength and (modulus of elasticity). Each group is divided into four subgroups according to fibers addition and to the alteration in powder-liquid ratio as follows: group (A) consists of (10 specimens) without the addition of glass fibers and with (3:1) powder- monomer ratio. Group (B) consists of (10 specimens) with addition of glass fibers and with (3:1) powder- monomer ratio, group (C) consists of (10 specimens) without addition of glass fibers and with (2.5:1) powder- monomer ratio and group (D) consists of (10 specimens) with glass fibers and with (2.5:1) powder- monomer ratio. The tensile strength and modulus of elasticity were determined by Instron testing machine at cross speed of 0.5mm/min. The T.R 200 device was used to indicate the values of surface roughness specimens before and after finishing and polishing. Results: In the present study, ANOVA test showed a significant difference at (P<0.05) between all the groups of tensile strength test.Least significant difference( LSD) test showed a non-significant difference at (P>0.05) between most of the tested groups except the groups of 3:1 powder–monomer ratio with and without fibers addition and groups of 3:1 ratio without fibers addition in comparison with the groups of 2.5:1 ratio with fibers addition which showed highly significant . The modulus of elasticity revealed a non-significant difference between all the tested groups at (P>0.05). While there were highly significant difference at (p<0.01) between groups of surface roughness test before and after polishing, except the group of 2.5:1 ratio with and without fibers addition which showed a non-significant difference at (P>0.05.). Conclusion: Conclusion was derived that fibers addition significantly affects tensile strength. The modulus of elasticity was not significantly affected by fibers addition or by powder-monomer ratio. Regarding surface roughness, it was improved after fibers addition and alteration in powder-liquid ratio.

Effect of Mechanical Tumbling Parameters on Surface Roughness and Edge Radius of Medical Grade Cobalt Chromium Alloy

Smoothly polished prosthesis surface is a crucial requirement in medical application and important feature that determine the proper response to corrosion and biocompatibility in the human body. Tumbling is one of the pre-polishing processes that can be conducted in order to improve the surface roughness of the machined prosthesis. However, the using of ceramic media for the tumbling process in medical application is not widely reported. This study was conducted to investigate the effect of mechanical tumbling parameters on the surface roughness of medical grade CoCr alloy by using alumina (Al2O3) based ceramic media. The experiment was performed with a different level of rotational speed (35, 55, and 75 rpm) and soaking time (4, 6 and 8 hours) of the tumbling process. The surface roughness of specimens before and after the process was measured using Mitutoyo Formtracer CS-5000 and the edge radius was measured using Olympus SZX9 microscope integrated with I-solution Lite software. It was figured that 6 hours tumbling time at 55 rpm showed the most significant reduction (32 %) in surface roughness (Ra) of the CoCr alloy specimen, while 8 hours tumbling time at 75 rpm showed the highest effect on the edge radius of the specimen at 63 % increment.

A study of prevalence and correlates of nonadherence to immunosuppressive medications in renal transplant recipients of South Indian population and their impact on long-term graft function.

Nonadherence to immunosuppressant medications leading onto poor graft outcome is frequent among renal transplant recipients. In this study, we sought to assess the prevalence and correlates of nonadherence to immunosuppressants and its impact on graft function. A singlecenter, retrospective cum cross-sectional study of renal transplant recipients of age >18 years and who had completed at least six months after transplantation was performed. Nonadherence was assessed based on the Immunosuppressant Therapy Adherence Scale questionnaire. Factors attributed to nonadherence were assessed based on the Immunosuppressant Therapy Barriers Scale (ITBS) questionnaire. Social, economic, demographic data, and all transplant related information were recorded. Two hundred and seventy-nine patients were included in the study, of whom 78% were male. Median follow-up period was 46 months (interquartile range - 24 months to 82 months). Seventy-four patients (26.5%) admitted nonadherence to immunosuppressants. The nonadherence was significantly related to the male gender, late acute rejection episodes, rise in serum creatinine from > 0.5 mg/dL from nadir level, lower blood levels of calcineurin inhibitor, and higher ITBS scores. Refill rates and use of alarm reminders were not significantly associated with better adherence.

Effect of Three Commonly Consumed Beverages on Surface Roughness of Polished and Glazed Zirconia-Reinforced Lithium Silicate Glass Ceramics.

Objectives:This study aimed to assess the effect of three commonly consumed beverages on surface roughness of polished and glazed zirconia-reinforced lithium silicate (ZLS) glass ceramics.Materials and Methods:In this experimental study, 104 rectangular specimens were cut from Vita Suprinity blocks with 2 mm thickness. After ultrasonic cleaning and firing of the specimens, they were finished and polished in two groups. Specimens in the first group were polished using a 2-step polishing kit while the second group specimens were glazed and heated in a porcelain firing oven according to the manufacturer’s instructions. Baseline surface roughness was measured using a profilometer. Specimens in each group were then randomly divided into 4 subgroups (n=13) for immersion in artificial saliva (control group), cola, orange juice and black tea. Surface roughness was measured again and data were analyzed using two-way ANOVA.Results:The highest and the lowest mean Ra were found in orange juice and saliva subgroups, respectively in both glazed and polished groups. The Ra values of both polished and glazed groups significantly increased after immersion in orange juice and cola (P<0.05). The polished surfaces showed insignificantly higher surface roughness compared with glazed surfaces (P>0.05).Conclusion:Orange juice and cola significantly increased the surface roughness of both polished and glazed ZLS ceramics. Type of surface finishing (polishing versus glazing) had no significant effect on the surface roughness of specimens following immersion in different beverages.

Effect of Surface Roughness on Fatigue Strength of Ti-6Al-4V Alloy Manufactured by Additive Manufacturing

This study focuses on the effects of surface roughness on the fatigue strength of Ti-6Al-4V alloy manufactured by additive manufacturing (AM); electron beam melting (EBM) and direct metal laser sintering (DMLS) methods. The hot isostatic pressing (HIP) was applied to some series of polished specimens and as-built specimens to eliminate internal defects. Fatigue limit was evaluated by rotating bending fatigue tests. Although HIP increased the fatigue limits slightly, the fatigue limits of as-built specimens with HIP were only about 30% of the ideal fatigue limit expected from the Vickers hardness. On the other hand, the polished specimens with HIP had the fatigue limit close to the ideal upper bound. The fatigue crack was initiated at multiple sites on the surface in as-built specimens. Thus, surface roughness has crucial influence on fatigue strength of AM component. The surface morphology of as-build specimen is three-dimensionally complex. The evaluation of equivalent defect size for surface roughness was attempt by √area parameter model assuming the surface roughness is a small defect. The estimated defect size was over the applicable range of the √area parameter model, suggesting that the surface roughness of as-built specimen should be considered as long crack.

Modeling of External Dynamics of Frictional Interaction Using the Elastic System Stability Theory

This work is focused on investigation into the surface structure of tribological pairs. The parametric identification is used to determine the main characteristics of the external dynamics of frictional interaction, namely, the damping coefficient, the natural oscillation frequency, and the dynamic friction coefficient. This method provides an opportunity to study in the real-time mode the evolution of friction processes of tribological pairs, which are accompanied by a change in the dynamic parameters. In turn, taking into account the influence of bifurcation processes associated with the loss of stability of individual elements of microcontacts, it is possible to match the dynamic characteristics of friction interactions with the measure of surface roughness of tribopair specimens.

Effect of cleansers on denture base resins' structural properties.

We assessed the effect of different available denture cleansers on the roughness and hardness of polyetherketoneketone, thermoinjection-molded polyamide, and polymethylmethacrylate. A total of 150 disc-shaped specimens were fabricated (10 mm × 2 mm) from these three denture base resins, and divided into five subgroups ( n = 10) according to immersion procedures. One of these groups subjected to distilled water served as control, whereas other groups were subjected to daily cleansing with four denture cleansers (Corega, Protefix, Curaprox, and Perlodent) for 8 h a day for 140 days. The surface roughness and hardness values of specimens were recorded by measuring twice at baseline, and again after application of chemical solutions. Topography alterations after treatments were assessed with scanning electron microscopy. The data were subjected to statistical analysis and comparison among groups was done using Kruskal Wallis and Wilcoxon Signed Ranks tests. P-value <0.05 was considered significant. The surface roughness of polyetherketoneketone, polymethylmethacrylate, and polyamide dentures was increased significantly by chemical solutions of denture cleansers. While the hardness value of polyetherketoneketone was not affected significantly after immersion in denture cleansers, those of polymethylmethacrylate and polyamide decreased significantly. Compared with Curaprox, the effervescent tablets significantly altered the surface hardness and roughness of polyamide. Denture cleansers can considerably alter the surface roughness and hardness of denture base resins and should be used carefully depending on the material.

Color stability, roughness, and water sorption/solubility of glass ionomer-Based restorative materials.

The aim of this study was to investigate the effects of various drinks on color stability and roughness of glass ionomer cement-based/-containing restorative materials and water sorption/solubility behavior of them. A total of 130 specimens for each material (GC Equia, GCP Glass Fill, Ketac N100, Glasiosite; a total of 520) were prepared using a Tefl on ring (7 × 2 mm). After specimen preparations, baseline color and surface roughness measurements were performed using a spectrophotometer and surface profi lometer, respectively. Specimens were immersed in four different solutions (n = 15; distilled water, cola, orange juice, and chocolate milk) during the 28-day test period. The immersion media were renewed daily. Color and surface roughness measurements were repeated at 1st, 7th, and 28th days. For water sorption, specimens (n = 15) were immersed in 10 mL of distilled water in individual containers and weighed at 1st week, 14th, and 28th days. After a total immersion time of 28 days, the specimens were dried to a constant mass, in a desiccator for 28 days. Each specimen was measured using a digital electronic caliper. Data were statistically analyzed (P < 0.05). After 28 days, the highest ΔE* value was calculated in GCP Glass Fill immersed in chocolate milk (10.54 ± 0.69). All the tested materials showed signifi cantly higher Ra values compared with baseline scores after immersion in various beverages regardless of the immersion solutions used (P < 0.05). Glasiosite showed the smallest water sorption (16.75 μg/mm3) among the tested materials, whereas Ketac N100 (155.41 μg/mm3) and GCP Glass Fill (161.01 μg/mm3) had the highest. The compositions of restorative materials play key roles in their color stability, surface roughness, and water sorption/solubility.

Effect of Denture Cleansers on Cobalt-Chromium Alloy Surface: A Simulated Period of 5 Years' Use.

To compare the effect of solutions of effervescent tablets (ET), cetylpyridinium chloride (CPC), and experimental solutions of Ricinus communis on the surface of cobalt-chromium (Co-Cr) alloys. Fifty-five specimens of Co-Cr were prepared by the lost-wax casting method using circular patterns (∅12 × 3 mm). The specimens were randomly divided into 5 groups: deionized water (control); 2% R. communis; 10% R. communis; ET, and CPC. The surface roughness of specimens (n = 10) was evaluated before immersion (baseline), and at simulated times of ½, 1, 2, 3, 4, and 5 years, by laser confocal microscope (Sa, μm) and profilometer (Ra, μm). The surface topography and chemical composition (n = 1) was qualitatively analyzed with scanning electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDS). Data were subjected to Kruskal-Wallis followed by Dunn tests, and Friedman followed by Wilcoxon tests (α = 0.05). For Sa, there was no difference for the solution factor. For the time factor a significant difference was found with 2% R. communis solution among baseline and ½, 2, 3, and 5 years (p < 0.001) and with 10% R. communis solution between 1 and 2 years (p = 0.007), with decreasing roughness over time. For Ra, cetylpyridinium chloride exhibited less roughness than 10% R. communis solution in ½ (p = 0.048) and 5 years (p = 0.013). In the SEM and EDS analysis the solutions did not present deleterious effects or changes in the chemical composition on the surfaces. Although a significant difference was found for the roughness, the results, below 0.2 μm, are clinically acceptable. Thus, all solutions can be used safely in removable partial denture cleaning for a period of 5 years.

Influence of rapid thermal annealing at varied temperatures on conductivity activation energy and structural properties of Si-doped β-Ga2O3 film grown by pulsed laser deposition

Si-doped β-Ga2O3 was generally activated by high-temperature annealing (over 600 °C) due to its strong bonding energy. Considering the electronic applications using β-Ga2O3 such as various power devices with low power consumption, it is strongly required to decrease the device process temperature including the impurity activation process. In this article, in order to decrease the impurity activation process temperature, we proposed the rapid thermal annealing (RTA) treatment to activate the Si atoms in the β-Ga2O3 films since RTA treatment can give the high thermal energy to specimen in a short time and investigated the influence of RTA treatment with various temperatures on conductivity activation energy, and structural properties of Si-doped β-Ga2O3 film. Si-doped β-Ga2O3 films were hetero-epitaxially grown on c-plane sapphire substrate by pulsed laser deposition method. Crystallinity, surface roughness, and electrical properties of specimens were investigated by changing the RTA temperatures. Crystallinity and surface roughness of Si-doped β-Ga2O3 films were not significantly influenced by RTA treatment at temperatures range of 100–700 °C. Conductivity activation energy of specimens with RTA treatment was about 50–100 meV and did not depend on RTA temperatures. As a result, even Si-doped β-Ga2O3 film with RTA treatment at 100 °C showed a relatively good conductivity. Based on the experimental results in this study, it can be said that RTA treatment is useful method to decrease the temperature of activation process for Si-doped β-Ga2O3 thin films without serious structural degradations.

Invitro comparison of wear characteristics of PyroCarbon and metal on bone: Shoulder hemiarthroplasty.

There are concerns regarding glenoid erosion with metal shoulder hemiarthroplasty. PyroCarbon may offer an alternative because of favorable wear characteristics and preservation of the glenoid. The purpose of this study was to assess invitro bone wear characteristics of PyroCarbon relative to cobalt chromium alloy hemiarthroplasty in a shoulder wear simulator. Wear of PyroCarbon and cobalt chromium prostheses articulating with bone were characterized by means of bone wear penetration rate, changes to surface roughness, and wear particle analysis. PyroCarbon prostheses produced significantly less damage to bone and were less damaged by the bone than cobalt chromium prostheses. Cobalt chromium testing was halted at approximately 320,000 cycles because the bone was consumed. Wear testing of PyroCarbon specimens continued through five million cycles. Linearized bone penetration rate, bone volume loss rate, and surface roughness for cobalt chromium test specimens were 30 times greater than for PyroCarbon. Results demonstrate significantly less damage to bone in simulated shoulder function testing for PyroCarbon hemiarthroplasty implants relative to conventional cobalt chromium implants. Our study supports use of PyroCarbon in humeral head hemiarthroplasty as a viable alternative to conventional metal hemiarthroplasty. Further investigation of PyroCarbon performance in clinical settings is warranted.