Fretting Fatigue Studies of Surface Modified Biomedical Titanium Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 681-686
Author(s):  
Aravind Vadiraj ◽  
M. Kamaraj
Keyword(s):  
Friction Coefficient ◽  
Titanium Alloys ◽  
Thermal Oxidation ◽  
Fatigue Damage ◽  
Plasma Nitriding ◽  
Normal Pressure ◽  
Fretting Fatigue ◽  
Laser Nitriding ◽  
Surface Modified

Fretting fatigue is a form of adhesive wear damage caused due to tangential micro motion of two contact bodies under normal pressure and cyclic load. Biomedical implants such as hip joints and bone plates undergo fretting fatigue damage leading to premature in-vivo failure and revision surgeries. Surface modification of implants delays the process of fretting and thereby improves the life of these medical devices. This work involves investigation of fretting fatigue damage of surface treated titanium alloys couple. The surface treatment involves PVD TiN coating, Plasma nitriding, Ion Implantation, Laser nitriding and thermal oxidation. Fretting of all surface treated alloys have shown both adhesive and abrasive mode of contact damage. Friction coefficient of all the surface treated pairs is less compared to uncoated alloys. Plasma nitrided pairs have shown the best performance in terms of fretting fatigue life and friction coefficient compared to all other coatings. Ion implanted pairs have shown little improvement in fretting fatigue lives due to shallow modified layer. PVD TiN coated pairs have irregular friction pattern due to abrasive particles at contact. Thermal oxidation and Laser nitriding have shown poor fretting fatigue performance due to high case thickness.

Effect of surface modified layers on fretting fatigue damage of biomedical titanium alloys

2006 ◽  
Vol 22 (9) ◽  
pp. 1119-1125 ◽  
Author(s):  
A. Vadiraj ◽  
M. Kamaraj ◽  
U. Kamachi Mudali ◽  
A. K. Nath
Keyword(s):  
Titanium Alloys ◽  
Fatigue Damage ◽  
Fretting Fatigue ◽  
Surface Modified ◽  
Effect Of Surface

scholarly journals Investigation of formation of hardened layer on titanium alloys by the method of ion-plasma nitriding

2019 ◽  
Vol 64 (1) ◽  
pp. 25-34
Author(s):  
I. L. Pobol ◽  
I. G. Oleshuk ◽  
A. N. Drobov ◽  
Sun Feng ◽  
Wang Lin
Keyword(s):  
Corrosion Resistance ◽  
Friction Coefficient ◽  
Titanium Alloys ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Saturation Pressure ◽  
Hardened Layer ◽  
Technological Parameters ◽  
Ion Plasma ◽  
Increase Wear Resistance

 Various methods are applied in the world practice to increase wear resistance, fatigue strength and corrosion resistance of aviation equipment, machinery and medicine parts made of titanium and its alloys. Ion-plasma nitriding provides the ultimate effect making it possible to obtain hardened layers with hardness of HV0.01 650–1000 with a thickness of 0.07–0.20 mm for 3–6 hours, depending on the grade of the titanium alloy.Technological factors effecting on the efficiency of ion-plasma nitriding of materials are the process temperature, duration of saturation, pressure, composition and flow rate of the working gas mixture. The effect of these technological parameters on the microstructure, microhardness and depth of hardened layers is investigated in the work. It is shown that hardness and depth of the nitrided layer can be controlled by changing the composition, volume and periodicity of the gaseous medium (nitrogen and argon) supply at the stages of heating and holding time of the samples from titanium and its alloys under ion-plasma nitriding. The tribological characteristics of titanium alloys as-received and the same ones subjected to ion-plasma nitriding under friction conditions without a lubricant were studied. For VT1-0 and VT6 alloys in the as-received state during the tests there is a monotonous decrease of the friction coefficient from 0.35–0.40 to 0.25, after nitriding the friction coefficient monotonically increases from 0.14 up to 0.30 when removing the hardened layer.Studies of corrosion resistance of titanium VT1-0, carried out in a 10 % solution of sulfuric acid, showed that after ion-plasma nitriding at a temperature of 830 °C for 6 hours, the corrosion resistance increases, as the positive polarization potential of the sample shows.

Pressure Changes Induced by Whole Body Acceleration Shocks

1991 ◽  
Vol 113 (1) ◽  
pp. 27-29 ◽  
Author(s):  
E. Belardinelli ◽  
M. Ursino ◽  
G. Fabbri ◽  
A. Cevese ◽  
F. Schena
Keyword(s):  
Mathematical Model ◽  
Carotid Artery ◽  
Normal Pressure ◽  
Compressed Air ◽  
Whole Body ◽  
Body Acceleration ◽  
Vascular Bed ◽  
Pressure Changes ◽  
The Mathematical Model

In the present paper pressure changes induced by sudden body acceleration are studied “in vivo” on the dog and compared to the results obtainable with a recently developed mathematical model. A dog was fixed to a movable table, which was accelerated by a compressed air piston for less than 1 s. Acceleration was varied by changing the air pressure in the piston. Pressure was measured during the experiment at different points along the vascular bed. However, only data obtained in the carotid artery and abdominal aorta are presented here. The results demonstrated that impulse body accelerations cause significant pressure peaks in the vessel examined (about + 25 mmHg in the carotid artery with body acceleration of g/2). Moreover, pressure changes are rapidly damped, with a time constant of about 0.1s. From the present results it may be concluded that, according to the prediction of the mathematical model, body accelerations such as those occurring in normal life can induce pressure changes well beyond the normal pressure value.

Effects of thermal oxidation on the effective thermal diffusivity of titanium alloys

2014 ◽  
Vol 47 (38) ◽  
pp. 385306 ◽  
Author(s):  
A Somer ◽  
F Camilotti ◽  
G F Costa ◽  
A R Jurelo ◽  
A Assmann ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Titanium Alloys ◽  
Thermal Oxidation ◽  
Effective Thermal Diffusivity
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