Tribological Study of Magnesium Alloys for Implant Applications

Author(s):  
Paul McGhee ◽  
Devdas Pai ◽  
Sergey Yarmolenko ◽  
Zhigang Xu ◽  
Sudheer Neralla ◽  
...  

Magnesium and its alloys have been found to potential candidates for biodegradable implant applications. However, magnesium and its alloys are broadly known to have poor tribological properties, but detailed specifics on wear performance are scarce. This research investigates the tribological characteristics on Mg-Zn-Ca-RE alloys and pure magnesium under as-cast and extruded conditions. Pure magnesium and Mg-Zn-Ca-RE alloys were hot extruded at 350°C and 400°C. Magnesium and Mg-Zn-Ca-Re alloy were also cast at 350°C and heat treated at 510°C. Directional wear properties were investigated using a CETR-UMT 2 microtribometer under unlubricated conditions in a reciprocating configuration for 120 cycles, with normal loads ranging from 0.5N–2.5N. Wear tests were conducted in directions: cross-sectional, longitudinal (along the extrusion direction) and transverse direction (perpendicular to the extrusion direction). Wear properties and friction properties were analyzed using a microtribometer, a mechanical stylus profiler, and microindentation. Surface morphology and microstructure were characterized using optical microscopy, scanning electron microscopy, and optical profilometry. The results show a lower wear rate in the transverse and cross-sectional direction compared to the longitudinal direction.

2018 ◽  
Vol 767 ◽  
pp. 196-203 ◽  
Author(s):  
Božo Skela ◽  
Marko Sedlaček ◽  
Bojan Podgornik

Good mechanical and wear properties of hot-work tool steels are needed for tools to withstand severe service conditions during their operational lifetime. Thus, the aim of this investigation was to correlate mechanical and wear properties with changes in microstructure of commercially available hot work tool steel Sitherm S361R. Hardness, impact toughness, tensile strength and wear tests were performed. Hot-work tool steel was heat treated at austenitizing temperature 1030 °C for 15 min in a horizontal vacuum furnace and gas quenched using nitrogen. One set of samples was investigated in as quenched state. Double tempering of samples was performed after quenching for 2 h at each of chosen temperatures, with first tempering temperature of 500 °C for the whole set of tempered samples. The second tempering was conducted at temperatures from 520 °C to 640 °C with increment of 30 °C for each set of samples. Microstructure of differently heat treated samples showed martensitic matrix, but different fraction and distribution of carbides, consequently influencing hardness, impact toughness, tensile strength, yield strength and wear resistance. Reciprocating sliding wear tests were carried out at room temperature in order to correlate microstructure of differently heat treated hot-work tool steel with wear. In order to achieve adhesive and abrasive wear mechanisms, 100Cr6 and Al2O3 balls were used as counter-body, respectively. Combination of adhesive and abrasive wear was observed for all specimens with different hardness when using 100Cr6 material as a counter body. However, in the case of Al2O3 abrasive wear was found as the prevailing wear mechanism.


2021 ◽  
Vol 9 ◽  
Author(s):  
Biao Ma ◽  
Bin Luo ◽  
Zhuozheng Wang ◽  
Chuiyi Meng ◽  
Xiujie He

Friction and wear performance is one of the key mechanical properties of accident tolerant fuel cladding coatings. In this study, reciprocating sliding wear tests had performed on two types of CrAl and CrAlN coatings with two different Al content ratios and Zr-4. The coefficient of friction, wear depth, and abrasion loss were measured and compared. The results indicated that the CrAl-based coatings improve the wear behavior significantly and nitrogen has an obvious improvement on the wear resistance of the coating. The friction and wear performance was also studied in a water environment. The results show that the presence of water degrade the wear performance of Zr-4 and CrAl coatings but ameliorates the friction and wear performance of CrAlN coatings. The feasibility of depositing ATF coating on conventional Zr-4 substrates to mitigate the influence of grid-to-rod fretting was demonstrated.


2021 ◽  
pp. 002199832110316
Author(s):  
Yavuz Sun ◽  
Engin Cevik ◽  
Yunus Turen ◽  
Hayrettin Ahlatci ◽  
Muhammet Emre Turan ◽  
...  

In this study, graphene nanoplatelets (GNPs) and boron carbide (B4C) nano reinforcements were incorporated to the pure magnesium (Mg). Powder metallurgy route was used to fabricate composite samples. Microstructures of specimens were examined and tensile, hardness, wear tests were performed to determine the mechanical and tribological performance of produced samples. The results indicate that the hardness was increased especially with the addition of 2% B4C and 0.5% GNPs reinforcements. A general trend was observed for the enhancements of yield and tensile strengths when nano reinforcements were added to the pure magnesium. The composite samples showed better wear resistance than the unreinforced sample. However, thermal conductivity began to decrease with the addition of B4C reinforcements. It is also observed that the porosity level was also higher for the composite samples.


2014 ◽  
Vol 42 (3) ◽  
pp. 166-184 ◽  
Author(s):  
Frédéric Biesse ◽  
Jérôme Mahé ◽  
Nicolas Lévy

ABSTRACT Tire tread wear is a key issue in the tire development process and for tire customers. In order to measure the wear performance, tire manufacturers usually proceed to wear tests and calculate the tire life from those tests. An important point in this tire life computation is the criteria chosen for defining the tire's end of life. In Europe, there is a legal minimum tread depth set to 1.6 mm applicable to 75% of the tread pattern width. However, outside those 75% (i.e., on the shoulder part), no clear and shared limit is defined. Also, the usual behavior of customers to decide when their tires should be changed is not well known. The goal of this 2012 study was to identify an average worn profile of tires in Europe and the behavior of customers for replacing their tires. For that, 3000 tires worn out by customers have been collected in scrapyards and measured in five European countries. In this article, we will present the tire collecting method, the measurement process, the analysis method, and some general results and statistics on this 3000 tire database. Finally, the method to compute the average end of life profile and the resulting profile is given.


Author(s):  
Vinayaka N ◽  
Avinash Lakshmikanthan ◽  
Manjunath Patel GC ◽  
Chithirai Pon Selvan ◽  
Vikram Kumar S Jain ◽  
...  

Author(s):  
DANIEL FRANCISCO MELLO ◽  
AMERICO HELENE JÚNIOR

ABSTRACT Objective: to describe the use of a superomedial fasciocutaneous thigh flap for scrotal reconstruction in open areas secondary to the surgical treatment of perineal necrotizing fasciitis (Fournier’s gangrene). Methods: retrospective analysis of cases treated at the Plastic Surgery Service of Santa Casa de Misericórdia, São Paulo, from 2009 to 2015. Results: fifteen patients underwent scrotal reconstruction using the proposed flap. The mean age was 48.9 years (28 to 66). Skin loss estimates in the scrotal region ranged from 60 to 100%. Definitive reconstruction was performed on average 30.6 days (22 to 44) after the initial surgical treatment. The mean surgical time was 76 minutes (65 to 90) to obtain the flaps, bilateral in all cases. Flap size ranged from 10cm to 13cm in the longitudinal direction and 8cm to 10cm in the cross-sectional direction. The complication rate was 26.6% (four cases), related to the occurrence of segmental and partial dehiscence. Conclusion: the superomedial fasciocutaneous flap of thigh is a reliable and versatile option for the reconstruction of open areas in the scrotal region, showing adequate esthetic and functional results.


2022 ◽  
Vol 327 ◽  
pp. 71-81
Author(s):  
Yun Xin Cui ◽  
Han Xiao ◽  
Chi Xiong ◽  
Rong Feng Zhou ◽  
Zu Lai Li ◽  
...  

The semi-solid extruded CuSn10P1 alloy bushings were homogenization annealed. The effects of annealing process on the hardness and wear properties of bushings were researched. The results show the Brinell hardness increases firstly and then decreases with the increase of annealing temperature and annealing time. With the annealing temperature increasing, the grinding loss rate and friction factor decrease firstly and then increase. At the annealing time of 120 min, the grinding loss rate decreases from 7% at the annealing temperature of 450 °C to 6% at 500 °C, and then increases from 6% at 500 °C to 12% at 600 °C. The friction factor decreases from 0.54 to 0.48 and then increases to 0.83. At the annealing temperature of 500 °C, the grinding loss rate decreases from 11% at the annealing time of 60 min to 6% at 120 min, and then increases to 15% at 150 min. The friction factor decreases from 0.67 to 0.48 and then increases to 0.72. The best wear performance and Brinell hardness can be obtained at annealing temperature of 500 °C for 120 min.


2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Mahsa Ebrahimi ◽  
Abbas Zarei-Hanzaki ◽  
A. H. Shafieizad ◽  
Michaela Šlapáková ◽  
Parya Teymoory

The present work was primarily conducted to study the wear behavior of as-received and severely deformed Al-15%Mg2Si in situ composites. The severe plastic deformation was applied using accumulative back extrusion (ABE) technique (one and three passes). The continuous dynamic recrystallization (CDRX) was recognized as the main strain accommodation and grain refinement mechanism within aluminum matrix during ABE cycles. To investigate the wear properties of the processed material, the dry sliding wear tests were carried out on both the as-received and processed samples under normal load of 10 and 20 N at room temperature, 100 °C, and 200 °C. The results indicated a better wear resistance of processed specimens in comparison to the as-received ones at room temperature. In addition, the wear performance was improved as the ABE pass numbers increased. These were related to the presence of oxide tribolayer. At 100 °C, the as-received material exhibited a better wear performance compared to the processed material; this was attributed to the formation of a work-hardened layer on the worn surface. At 200 °C, both the as-received and processed composites experienced a severe wear condition. In general, elevating the temperature changed the dominant wear mechanism from oxidation and delamination at room temperature to severe adhesion and plastic deformation at 200 °C.


2016 ◽  
Vol 51 (19) ◽  
pp. 2805-2812 ◽  
Author(s):  
G Miranda ◽  
M Buciumeanu ◽  
MM Costa ◽  
F Bartolomeu ◽  
FS Silva ◽  
...  

This study is concerned with the influence of four metallic reinforcements on aluminum-silicon (AlSi) composites, with respect to wear behavior. AlSi-Ti; AlSi-Ti6Al4V; AlSi-1.4301 stainless steel and AlSi-Ni particulate reinforced composites were produced by a hot-pressing route. Microstructural characterization showed a uniform distribution of the reinforcing particles in the AlSi matrix. Reciprocating pin-on-plate wear tests were performed for AlSi and AlSi-based composites against gray cast iron plates. In order to compare the effect of different metallic particulates on the AlSi-based composites/gray cast iron tribopair wear performance, besides the pin, the counterface was also analyzed. The particle/matrix interface is analyzed in order to understand its influence on the tribopair behavior and on the controlling wear mechanisms. It was shown that the better compromise between both sliding surfaces performance was attained by AlSi-Ni/gray cast iron tribopair.


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