Directional-Tribological Investigation of Magnesium Alloys Under As-Cast and Hot Extrusion Conditions

2015 ◽  
Author(s):  
Paul McGhee ◽  
Devdas Pai ◽  
Sergey Yarmolenko ◽  
Jagannathan Sankar ◽  
Zhigang Xu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Wear Rate ◽  
Cross Section ◽  
Cross Sections ◽  
Transverse Direction ◽  
Longitudinal Section ◽  
Mg Alloy ◽  
Wear Properties ◽  
Wear Coefficient

In recent years, magnesium (Mg) and its alloy are being studied for their potential use in orthopedic implants with the novel ability to biodegrade after the implant serves its therapeutic function. Pure Mg, by itself, would not be suitable for use in a load-bearing implant application, due to its high corrosion rate and poor tribological properties. However, through proper alloying, this degradable metal is capable of achieving good mechanical properties reasonably similar to bone, a retarded rate of corrosion and enhanced biocompatibility. Previous studies have shown that alloying Mg with aluminum, lithium, rare earth (RE), zinc (Zn), and calcium (Ca) result in lower corrosion rates and enhanced mechanical properties. Despite the growing popularity of Mg and it alloys, there is relatively little information in the literature on their wear performance. In this paper, we report on an investigation of the directional tribological properties of Mg and Mg-Zn-Ca-RE alloy fabricated via two different manufacturing processing routes: as-cast and hot-extruded after casting, with extrusion ratios of 10 and 50. Pure Mg was cast 350°C. After casting, Mg-Zn-Ca-RE alloy was heat-treated at 510°C. Another Mg-Zn-Ca-RE alloy was hot-extruded at 400°C. Dry sliding wear tests were performed on as-cast and hot-extruded pure Mg and Mg-Zn-Ca-RE alloys using a reciprocating test configuration. Wear rate, coefficient of friction and wear coefficient were measured under applied loads ranging from 0.5–2.5N at sliding frequency of 0.2 Hz for 120 cycles, using microtribometery. Wear properties of the extruded specimen were measured in cross-section and longitudinal section. In the longitudinal section studies, wear properties were investigated along the extrusion direction and the transverse direction. Hardness properties were evaluated using microindentation. Cross-section and longitudinal section were indented with a Vickers indenter under applied load of 2.94 N. Alloying and extrusion enhanced the mechanical properties significantly, increased hardness by 80% and wear resistance by 50% compared to pure Mg. Despite the low hardness in both Mg and the Mg alloy cross-sections, the cross-sections for both displayed higher wear resistance compared to the longitudinal section. In the longitudinal section, wear resistance was higher along the transverse direction of the longitudinal section for both Mg and the Mg alloy. The wear coefficient was used to evaluate how the wear behavior of the material varied with respect to alloying, fabrication process, and direction of wear. The wear coefficient of pure Mg decreased as the extrusion ratio increased, thus, increasing the specific wear rate. The opposite behavior was found in the Mg alloy: as the wear coefficient increases, the specific wear rate decreases. The active wear mechanisms observed on the worn surface of Mg were fatigue, abrasive, adhesive and delamination wear. The same wear mechanisms were observed in the Mg alloy except for fatigue wear. Surface microstructure and topographical characterization were conducted using optical microscopy, scanning electron microscopy mechanical stylus profilometry, and optical profilometry.

Evaluation of changes in mechanical properties of O-ring in one-piece and two-piece ball retained implant-supported overdentures: A three-year retrospective study.

2021 ◽  
Author(s):  
Fathima Banu Raza ◽  
Anand Kumar
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Retrospective Study ◽  
Statistical Analysis ◽  
Wear Rate ◽  
Digital Camera ◽  
Maximum Displacement ◽  
Pin On Disc ◽  
The One ◽  
Insight Into

The o-rings in ball retained overdentures deteriorate with time and need replacement to restore the retentive quality. We evaluated retrospectively the mechanical properties of o-rings after 3 years in function in one and two-piece implant-supported overdentures. The o-rings were retrieved from one-piece (Myriad snap, Equinox-Straumann, 3.3 x 13mm) and two-piece (Neo Biotech, 3.3 x 13mm) implant-supported overdenture patients. A total of 16 pairs of matrices were tested for wear, type of damage and elasticity using Pin on Disc method, USB Digital Camera in 30x zoom and Universal Tensile Machine respectively. The statistical analysis for independent groups were done with the Mann-Whitney U test. Assessment of used O-rings showed 84% more wear in the two-piece system with an abrasive type of damage while 46% wear in the one-piece system with a compressive type of damage. The o-rings in one-piece system showed increase in elongation and maximum displacement to 2% and 7% respectively, while two-piece system showed decrease in elongation and maximum displacement by 13% and 6% respectively. In one-piece system, the loss of retention was more with slow wear rate and in two-piece system, the wear resistance of O-rings decreased due to increased stiffness. Further studies to evaluate the changes in O-ring with increased sample size and at interval 1 year will pave way for insight into the progressive changes in the mechanical properties of an O-ring.

Wear Properties of Y-TZP Ceramics Dispersed with Second Phase Particles

2008 ◽  
Vol 368-372 ◽  
pp. 744-747
Author(s):  
Xiao Ping Liang ◽  
Shao Bo Xin ◽  
Xiao Hui Wang ◽  
Zheng Fang Yang
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Mass Fraction ◽  
Normal Load ◽  
Roller Bearing ◽  
Second Phase ◽  
Wear Properties ◽  
Wear Rates ◽  
Second Phase Particles ◽  
Better Than

The wear properties of ADZ (alumina dispersed in Y-TZP) and MDZ (mullite dispersed in Y-TZP) were investigated by using a ring-on-block tribometer. The results showed that for Y-TZP ceramic, the addition of alumina phase (with 10-20% in mass fraction) leads to an improved wear resistance. With the increase of the normal load, the wear rates of ADZ ceramics increase. Under low and medium normal load (100N and 300N), the wear resistance is controlled by the hardness of ceramics, and under high normal load (500N) the fracture toughness is obviously contributed to the wear resistance of the ceramics. For MDZ ceramic, the wear resistance of 15MDZ (15wt% mullite dispersed in Y-TZP) is better than that of 20 MDZ (20wt% mullite) under the normal load from 100 N to 500 N. The mechanical properties of 15MDZ are worse than that of Y-TZP ceramic, but the wear resistance is enhanced due to the action of “needle roller bearing” of the fractured rod-like mullite particles.

Effects of Laser Shock Peening on the Wear and Degradation Behaviors of Magnesium Alloys

2016 ◽  
Author(s):  
Ruixia Zhang ◽  
Xiaoning Hou ◽  
Xianfeng Zhou ◽  
Hongyu Gao ◽  
Steven Mankoci ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Body Fluid ◽  
Laser Shock Peening ◽  
Mg Alloy ◽  
Laser Shock ◽  
Before And After ◽  
Immersion Testing ◽  
Degradation Behaviors ◽  
Shock Peening

In this study, we investigated the mechanical properties of AZ31B Mg alloy before and after laser shock peening (LSP). The hardness of the AZ31B Mg alloy increased from 57 HV to 69 HV after LSP. The yield strength increased from 128 MPa to 152 MPa. Wear resistance was significantly improved after LSP. Immersion testing showed that LSP did not significantly increase the element release and weight loss in simulated body fluid. We have demonstrated that LSP is an effective way to improve the mechanical properties of the AZ31B Mg alloy.

The Brittleness of Ebonite

1937 ◽  
Vol 10 (4) ◽  
pp. 778-786
Author(s):  
R. Ariano
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Cross Sections ◽  
Test Specimen ◽  
The State ◽  
The Other ◽  
Appreciable Effect ◽  
Considerable Influence ◽  
Minimum Depth ◽  
The Moment

Abstract The results of tests of the brittleness of ebonite are described. Resilience is influenced chiefly by the moment of inertia of the cross section of the test-specimen, but it seems also to be affected by the form of the specimen. The state of vulcanization has considerable influence on these mechanical properties within the undercured range, but with thorough vulcanization the state of cure plays no appreciable part. Notching of test-specimens is not of great importance. It diminishes the resilience, but when the tests are compared on a basis of equal moments of inertia of the resistant cross sections, this diminution becomes inappreciable in the case of brittle ebonites. On the other hand, the shape of the notch in ebonites containing no loading ingredients does influence the resilience. With V-shaped notches, the depth of the notch and its angle of aperture influence considerably the resilience of this latter type of ebonite, and notches of minimum depth are sufficient to have an appreciable effect.

Effect of Testing Parameters on Wear Properties of Alumina Strengthen 3Y-TZP Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 2468-2471 ◽  
Author(s):  
Shi Hai Zhao ◽  
Shao Bo Xin ◽  
Xiao Hui Wang ◽  
Xiao Ping Liang
Keyword(s):  
Wear Resistance ◽  
Wear Rate ◽  
Abrasive Particle ◽  
High Load ◽  
Wear Properties ◽  
Testing Conditions ◽  
High Chromium ◽  
High Chromium Cast Iron ◽  
Low Load ◽  
Chromium Cast Iron

The wear behaviours of alumina strengthen 3Y-TZP ceramics worn against high chromium cast iron under various testing conditions were investigated using a block-on-block tribometer. The results showed that the wear rate increases with the increasing of the load and the sliding time. Under the low load the main mechanism governing the wear properties of ceramic is the apparent plastic deformation and ploughing, and the wear rate rapidly increases and the wear mechanism changes into brittle fracture under high load. Meanwhile the wear resistance is depended on the properties of the abrasive particle. As expected, the wear resistance was increased with decreasing hardness of abrasive particle, but it was also influenced by the morphology, that is, the sharper the abrasive particle the higher wear rate.

Hardness as a Measure of Wear Resistance

1983 ◽  
Vol 27 ◽  
Author(s):  
W.C. Oliver ◽  
R. Hutchings ◽  
J.B. Pethica ◽  
I.L. Singer ◽  
G.K. Hubler
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Wear Rate ◽  
Wear Mechanism ◽  
Chemical Nature ◽  
Bearing Steel ◽  
Mechanical Properties Of Materials ◽  
Microhardness Data ◽  
Properties Of Materials ◽  
Ion Implanted

ABSTRACTOne measure of the surface mechanical properties of materials can be obtained through microhardness data. The success of microhardness in predicting the improvements in wear resistance of ion implanted metals has been mixed. In this paper the cases of N implantation into 304 S.S. and Ti implantation into 52100 bearing steel will be examined. Microhardness data indicates little or no hardness changes whereas large wear rate changes are observed. From these two examples it is clear that the wear mechanism, the chemical nature of the surface, the ductility, and the toughness can be more important than the hardness changes.

Wear Behaviour of HVOF Sprayed WC-Cobalt Coatings

2011 ◽  
Vol 326 ◽  
pp. 144-150
Author(s):  
A. Mateen ◽  
Fazal Ahmad Khalid ◽  
T.I. Khan ◽  
G.C. Saha
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
High Hardness ◽  
Wear Behaviour ◽  
Wear Properties ◽  
Coating Structure ◽  
Superior Mechanical Properties ◽  
Cobalt Coating ◽  
Mining Tools ◽  
Duplex Coatings

Tungsten carbide cobalt coating has been extensively used for cutting and mining tools, aerospace, automotive and other wear resistance applications. These coatings not only have superior mechanical properties like high hardness, toughness and compressive strength but have also excellent controllable tribological properties. In this paper a comparison of wear properties and structural phases has been presented to consider for tribological applications. It is found that nanocrystalline duplex coatings have shown much superior properties as compared to the microcrystalline coatings. Evidence of clusters of WC particles was found in microcrystalline coating as compared to homogeneous dense coating structure observed in the nanocrystalline coating. These results are discussed to assess their suitability for super hard wear resistance applications.

Efficiency of visual strength grading of timber with respect to origin, species, cross section, and grading rules: a critical evaluation of the common standards

Holzforschung ◽  
2014 ◽  
Vol 68 (2) ◽  
pp. 203-216 ◽  
Author(s):  
Peter Stapel ◽  
Jan-Willem G. van de Kuilen
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Cross Sections ◽  
Critical Evaluation ◽  
International Standards ◽  
National Standards ◽  
Visual Grading ◽  
Source Areas ◽  
The Common ◽  
Machine Strength

Abstract Strength grading is essential for the efficient use of structural timber. Although international standards exist for machine strength grading, visual grading is still regulated based on national rules, which are expected to allow safe and economic grading results. Although there are large differences in the graded output because the species, the cross section, and the origin of the timber influence the results, some of these standards are considered to be applicable universally. The present article demonstrates how the chosen standards influence the grading results. Depending on the parameters, the yields or the mechanical properties are low compared with the declared values. The results also show the efficiency and applicability of different national standards for strength grading of timber from various origins. Furthermore, it is recommended to reconsider the existing limits for source areas and cross sections given in the standard EN 1912.

Investigations on tribological behaviour of AA7075-TiO2 composites under dry sliding conditions

2019 ◽  
Vol 71 (9) ◽  
pp. 1064-1071 ◽  
Author(s):  
Alagarsamy S.V. ◽  
Ravichandran M.
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Friction Coefficient ◽  
Wear Rate ◽  
Applied Load ◽  
Weight Ratio ◽  
Specific Wear Rate ◽  
Dry Sliding ◽  
Matrix Composites ◽  
Content Type

Purpose Aluminium and its alloys are the most preferred material in aerospace and automotive industries because of their high strength-to-weight ratio. However, these alloys are found to be low wear resistance. Hence, the incorporation of ceramic particles with the aluminium alloy may be enhanced the mechanical and tribological properties. The purpose of this study is to optimize the specific wear rate and friction coefficient of titanium dioxide (TiO2) reinforced AA7075 matrix composites. The four wear control factors are considered, i.e. reinforcement (Wt.%), applied load (N), sliding velocity (m/s) and sliding distance (m). Design/methodology/approach The composites were fabricated through stir casting route with varying weight percentages (0, 5, 10 and 15 Wt.%) of TiO2 particulates. The mechanical properties of the composites were studied. The specific wear rate and friction coefficient of the newly prepared composites was determined by using a pin-on-disc apparatus under dry sliding conditions. Experiments were planned as per Taguchi’s L16 orthogonal design. Signal-to-noise ratio analysis was used to find the optimal combination of parameters. Findings The mechanical properties such as yield strength, tensile strength and hardness of the composites significantly improved with the addition of TiO2 particles. The analysis of variance result shows that the applied load and reinforcement Wt.% are the most influencing parameters on specific wear rate and friction coefficient during dry sliding conditions. The scanning electron microscope morphology of the worn surface shows that TiO2 particles protect the matrix from more removal of material at all conditions. Originality/value This paper provides a solution for optimal parameters on specific wear rate and friction coefficient of aluminium matrix composites (AMCs) using Taguchi methodology. The obtained results are useful in improving the wear resistance of the AA7075-TiO2 composites.

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