Surface Engineering to Improve the Durability and Lubricity of Ti-6Al-4V Alloy

Scratch resistance analysis of plasma-nitrided Ti–6Al–4V alloy

Plasma nitriding of the Ti-6Al-4V alloy (TA) sample was carried out in a plasma reactor with a hot wall vacuum chamber. For ease of comparison these plasma nitrided samples were termed as TAPN. The TA and TAPN samples were characterized by XRD, Optical microscopy, FESEM, TEM, EDX, AFM, nanoindentation, micro scratch, nanotribology, sliding wear resistance evaluation and in vitro cytotoxicity evaluation techniques. The experimental results confirmed that the nanohardness, Young’s modulus, micro scratch wear resistance, nanowear resistance, sliding wear resistance of the TAPN samples were much better than those of the TA samples. Further, when the data are normalized with respect to those of the TA alloy, the TAPN sample showed cell viability about 11% higher than that of the TA alloy used in the present work. This happened due to the formation of a surface hardened embedded nitrided metallic alloy layer zone (ENMALZ) having a finer microstructure characterized by presence of hard ceramic Ti2N, TiN etc. phases in the TAPN samples, which could find enhanced application as a bioimplant material.

Nano- and micro-tribological behaviours of plasma nitrided Ti6Al4V alloys.

This study experimentally investigated the effect of surface textures on the tribological mechanism of nitrided titanium alloy (Ti–6Al–4V). The titanium alloy samples were nitrided at various temperatures ranging from 750 to 950 °C for 10 h in a plasma nitriding furnace. Then, surface textures were fabricated on the polished titanium alloy and plasma nitrided samples by laser process system. The surface roughness, microhardness, and constitution of samples treated by single nitriding and samples treated by composite technology were characterized. The tribological properties of the samples were investigated on a CSM ball-on-disc tribometer. The results show that plasma nitriding effectively enhances the wear resistance of the substrate. The wear rate decreases first and then increases with the increase of nitriding temperature, and the wear rate reaches the minimum at 900 °C. However, the increase in roughness caused by nitriding treatment leads to an increase in the friction coefficient. It is found that surface textures can obviously reduce the friction coefficient of the nitrided titanium alloy. In addition, it can also reduce the wear rate of titanium alloys after nitriding at 900 and 950 °C. It can be concluded that the nitriding and surface texturing combined treatment can obviously reduce the friction coefficient and wear rate at the nitriding temperatures of 900 and 950 °C. This is attributed to the combined effect of high hardness of nitride layers and the function of micro-trap for wear debris of surface textures.

https://www.mdpi.com/1996-1944/12/2/301/pdf

Tribological Behavior of Titanium Alloy Treated by Nitriding and Surface Texturing Composite Technology

Effects of combined diffusion treatments and cold working on the sliding friction and wear behavior of Ti–6Al–4V ☆

In order to improve the poor surface hardness and the wear resistance, titanium has been nitrided with plasma (ion) nitriding which is one of the methods to treat surface properties of titanium alloys. The increment at surface hardness and so the wear resistance of nitrided titanium alloys has been provided by means of compound layer (e-Ti2N+δ-TiN) and diffusion zone (α-Ti) occurred by plasma ion nitriding. The goal of the present paper is to investigate effects of nitriding temperature and nitriding time on the microstructure and hardness value of nitrided surface layers. A systematic study was undertaken with specimens of commercial pure Ti and Ti-6Al-4V alloy. As treatment parameters, we have used; nitriding time (from 2 to 9 hour), nitriding atmosphere (H2-80%N2), total pressure (1 kPa) and cathode temperature (from 600 to 800 oC). The Vickers indenter was used for analysis of the micro hardness measurements. The thin hardened layer at the nitrided surface was characterized by glancing-angle X-ray difractometer. X-ray diffraction analysis has confirmed the formation of e-Ti2N and δ-TiN phases on the nitrided specimens. Experimental details and characterization of plasma (ion) nitrided titanium have reported and discussed.

Treatment of Surface Properties of Titanium with Plasma (Ion) Nitriding

In this study, production of alumina and steatite containing ceramic insulators as thermostat material was realized by investigating the composition, pressing pressure and sintering temperature. 90...

Production and Characterization of Alumina and Steatite Based Ceramic Insulators

Production of B4C-TiB2 composite powder by self-propagating high-temperature synthesis

Abstract Magnesium and its alloys are excellent implant material candidates with their biodegradable structure and mechanical properties close to human bone. In order to provide the desired strength in implant applications, the corrosion resistance of the materials is expected to be high. In this study, to improve the corrosion resistance of AZ31 and AZ91 magnesium alloys, an electrostatic hydroxyapatite coating process was applied, and optimum conditions were determined. The samples were structurally characterized by scanning electron microscopy/energy dispersive X-ray spectroscopy and stereo microscopy methods, and their corrosion behavior was determined by the weight loss method. As a result of the coating, the corrosion resistance of the samples increased up to 250 %.

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Corrosion behavior of hydroxyapatite coated AZ31 and AZ91 Mg alloys by electrostatic spray coating

Corresponding to the technological developments, production and consumption of nickel have increased greatly over time due to its unique mechanical and chemical properties. Therefore, the production of nickel will always keep its importance. The availability of laterite ores, which are oxide type ores, is 86% of the nickel reserves on the Earth, and the processes used in the production of nickel from sulfide type ores have negative environmental effects. Therefore, recovery of nickel from lateritic ores has become increasingly important in recent years. In this study, the aim was to determine the optimum parameters of nickel and cobalt production from limonite type lateritic nickel ores, which were taken from Manisa Caldag region of Turkey, using atmospheric pressure sulfuric acid leaching and pug-roast-leach process. When the results obtained in these processes were compared, it was found that the Ni leaching efficiency is nearly 8% higher and iron leaching efficiency (contamination) is nearly 4% lower in the pug-roast-leach process. Furthermore, the pug-roast-leach process was completed in 33% lower time compared to the atmospheric pressure sulfuric acid leaching process.

/pdf/hydrometallurgical-nickel-and-cobalt-production-from-yzmhp0jlcz.pdf

Hydrometallurgical nickel and cobalt productıon from lateritic ores: Optimization and comparison of atmospheric pressure leaching and pug-roast-leaching processes

Mahmut Ercan Açma

Papers

Treatment of Surface Properties of Titanium with Plasma (Ion) Nitriding

Production and Characterization of Alumina and Steatite Based Ceramic Insulators

Production of B4C-TiB2 composite powder by self-propagating high-temperature synthesis

Corrosion behavior of hydroxyapatite coated AZ31 and AZ91 Mg alloys by electrostatic spray coating

Hydrometallurgical nickel and cobalt productıon from lateritic ores: Optimization and comparison of atmospheric pressure leaching and pug-roast-leaching processes