Titanium oxynitrides combine the properties of metallic oxides and nitrides. In this presentation, titanium was oxynitrided using inductively coupled RF plasma in a gas mixture containing 80% N2 and 20% O2. The effect...Titanium oxynitrides combine the properties of metallic oxides and nitrides. In this presentation, titanium was oxynitrided using inductively coupled RF plasma in a gas mixture containing 80% N2 and 20% O2. The effect of plasma-processing power from 350 up to 550 W on microstructure, mechanical, tribological, wettability and electrochemical properties of the oxynitrided titanium was examined using different characterizations and testing techniques. The results demonstrated the formation of TiO, TiO2 rutile phase, TiNxOy and Ti2N as a result of plasma oxynitriding. The micro-hardness of the oxynitrided layers increases up to 766 HV0.1 as the plasma-processing power increases up to 550 W. The wear and corrosion resistance are improved for oxynitrided titanium in comparison with untreated samples. Moreover, the friction coefficient decreases from nearly 0.75 for the pure titanium to nearly 0.3 for oxynitrided titanium. The obtained data show an increase of surface energy and wettability of titanium oxynitride as the plasma power increases. The formation of hard oxide and oxynitride phases and the transformation of TiO2 from anatase to rutile structure at relatively high temperature are the main reasons for the good physical and electrochemical properties of titanium oxynitride.展开更多
A surface-hardening treatment for AZ31 magnesium alloy using an atmospheric-pressure plasma jet(APPJ)at room temperature was developed.Magnesium is a potential engineering material because it is lightweight;however,ma...A surface-hardening treatment for AZ31 magnesium alloy using an atmospheric-pressure plasma jet(APPJ)at room temperature was developed.Magnesium is a potential engineering material because it is lightweight;however,magnesium alloys are difficult to heat-treat because of their low flaming temperature.Magnesium alloy specimens were irradiated with a localized atmospheric-pressure plasma jet generated by dielectric-barrier discharge for 180 s in air.The APPJ excited oxygen and nitrogen molecules in the ambient air,resulting in the formation of an oxynitrided layer;oxygen and nitrogen diffusion layer,on the surface of the magnesium alloy.The hardness and elemental distribution for the treated surface were examined.The top surface of the APPJ-treated magnesium alloy achieved a maximum hardness of 108 HV,which was~1.7 times greater than that of the untreated surface.Elemental analysis using an electron-probe microanalyzer revealed strong oxygen and nitrogen signals corresponding to the hardened region of the magnesium alloy,meaning that the hardness increased as a result of the formation of the oxynitrided layer.The proposed APPJ treatment is a promising approach for locally hardening magnesium alloys without using a heat treatment.展开更多
文摘Titanium oxynitrides combine the properties of metallic oxides and nitrides. In this presentation, titanium was oxynitrided using inductively coupled RF plasma in a gas mixture containing 80% N2 and 20% O2. The effect of plasma-processing power from 350 up to 550 W on microstructure, mechanical, tribological, wettability and electrochemical properties of the oxynitrided titanium was examined using different characterizations and testing techniques. The results demonstrated the formation of TiO, TiO2 rutile phase, TiNxOy and Ti2N as a result of plasma oxynitriding. The micro-hardness of the oxynitrided layers increases up to 766 HV0.1 as the plasma-processing power increases up to 550 W. The wear and corrosion resistance are improved for oxynitrided titanium in comparison with untreated samples. Moreover, the friction coefficient decreases from nearly 0.75 for the pure titanium to nearly 0.3 for oxynitrided titanium. The obtained data show an increase of surface energy and wettability of titanium oxynitride as the plasma power increases. The formation of hard oxide and oxynitride phases and the transformation of TiO2 from anatase to rutile structure at relatively high temperature are the main reasons for the good physical and electrochemical properties of titanium oxynitride.
基金the Tanikawa Fund Promotion of Thermal Technology and the Light Metal Education Foundation。
文摘A surface-hardening treatment for AZ31 magnesium alloy using an atmospheric-pressure plasma jet(APPJ)at room temperature was developed.Magnesium is a potential engineering material because it is lightweight;however,magnesium alloys are difficult to heat-treat because of their low flaming temperature.Magnesium alloy specimens were irradiated with a localized atmospheric-pressure plasma jet generated by dielectric-barrier discharge for 180 s in air.The APPJ excited oxygen and nitrogen molecules in the ambient air,resulting in the formation of an oxynitrided layer;oxygen and nitrogen diffusion layer,on the surface of the magnesium alloy.The hardness and elemental distribution for the treated surface were examined.The top surface of the APPJ-treated magnesium alloy achieved a maximum hardness of 108 HV,which was~1.7 times greater than that of the untreated surface.Elemental analysis using an electron-probe microanalyzer revealed strong oxygen and nitrogen signals corresponding to the hardened region of the magnesium alloy,meaning that the hardness increased as a result of the formation of the oxynitrided layer.The proposed APPJ treatment is a promising approach for locally hardening magnesium alloys without using a heat treatment.
文摘在783～843 K温度范围和不同保温时间（30～240 min）对45钢进行了离子氮氧共渗和离子渗氮表面改性处理,对比研究了两种处理方法的动力学。离子氮氧共渗是在离子渗氮的基础上添加流量为0.2 L/min的空气实现的。利用光学显微镜和X射线衍射仪对化合物层显微组织、厚度及物相组成进行了测试和分析。结果表明,添加适量空气可显著促进活性氮原子在基体内的扩散,离子氮氧共渗的扩散系数比普通离子渗氮显著提高,扩散激活能从227.25 k J/mol降低到138.57 k J/mol,从而可达到降低温度或缩短保温时间的效果。同时,计算得到了45钢在783~843 K温度范围内离子氮氧共渗时化合物层厚度与温度T（K）和保温时间t（s）的动力学关系式。
