Mechanical and acoustic characteristics of oxidized, nitrided and oxynitrided Zr-1%Nb zirconium alloy

The effect of the gaseous medium composition during thermo-chemical treatment (TCT) on the mechanical properties and acoustic parameters of Zr-1%Nb zirconium alloy was studied. It is shown that TCT in oxygen-nitrogen contained gaseous media significantly increases the surface hardness and does not worsen the mechanical characteristics (including their plasticity) of zirconium alloy which is used as a material for case of fuel nuclear rod. It is established that TCT in different mediums also influences on acoustic parameters of the Zr-1%Nb alloy. Noticeable changes in the acoustic parameters observed at the initial stage of deformation are associated with the features of the destruction of a thin film formed on the zirconium alloy surface after TCT.Наведено дані щодо впливу складу газового середовища, в якому проводили хіміко-термічну обробку (ХТО), на механічні властивості та акустичні параметри зразків із сплаву цирконію Zr-1%Nb. Показано, що ХТО за вибраними режимами в кисневмісному, азотовмісному та азотокисневмісному газових середовищах суттєво збільшує твердість поверхневого шару зразків сплаву цирконію та не погіршує механічні характеристики зразків твельних оболонок, у тому числі їх пластичність. Показано, що за впливом середовища ХТО на характеристики сплаву акустичні параметри виявилися більш інформативними порівняно з механічними властивостями. Зроблено припущення, що помітні зміни акустичних параметрів, що спостерігаються на початковій стадії деформування, пов’язані з особливостями руйнування тонкої плівки, що утворюється на поверхні трубки в результаті ХТО

Tribological behavior of Ti–6Al–4V matrix composites reinforced with TiC

The tribological properties of the composite reinforced with TiC carbide particles synthesized on the base of Ti–6Al–4V titanium alloy were investigated. It was determined that the wear resistance of the TMCs compared to Ti–6Al–4V titanium alloy, obtained by the method of powder metallurgy, in the friction pairs with Cu–10Al–4Fe–4Ni bronze and Fe–0.45C hardened steel under the conditions of boundary lubrication increased by 11 and 1.3 times, respectively. The wear mechanisms of the investigated tribopairs were determined. It was shown that due to the addition of solid TiC inclusions into Ti–6Al–4V alloy matrix, the wear mechanism of the friction pairs was changed from adhesion-fatigue to abrasive-fatigue

Wear resistance of two-phase titanium alloy after deformation-diffusion treatment

The influence of deformation-diffusion treatment including a combination of the previous cold surface plastic deformation (ball burnishing) and subsequent thermochemical treatment (nitriding), on the tribological behavior of the Ti–6Al–5Mo–5V–1.5Cu–1Fe two-phase titanium alloy in a pair with Cu–10Al–4Ni–4Fe bronze alloy was studied. According to the results of the tribological test, SEM and EDX analyses of the wear surfaces, wear mechanisms (or processes) those of tribo-pairs in the conditions of boundary lubrication were established. It is shown that deformation-diffusion treatment of titanium alloy provided higher tribotechnical parameters (wear resistance, friction coefficient, temperature near the friction zone) of investigated tribo-pairs compared to traditional treatments (ball burnishing or nitriding)Vytauto Didžiojo universitetasŽemės ūkio akademij

Influence of oxynitriding on antifriction properties of Ti–6Al–4V titanium alloy

Russian Text, published in Trenie i Iznos, 2020, Vol. 41, No. 4, pp. 457–463The wear resistance of a plate–screw tribo pair used to fix bone fractures was investigated using the pin-on-plate configuration under conditions of dry friction and friction in Ringer’s solution. The nitrided and oxynitrided plates of Ti–6Al–4V titanium alloy in friction pairs with Fe–18Cr–10Ni–1Ti stainless steel were used. It was determined that under dry friction conditions, regardless of load, the nitrided Ti–6Al–4V titanium alloy provides a lower friction coefficient than the oxynitrided one; friction is implemented according to the adhesive wear mechanism. The use of Ringer’s solution during friction tests leads to an adhesive– oxidative wear mechanism that decreases the friction coefficient in friction pairs of nitrided (oxynitrided) Ti– 6Al–4V titanium alloy–Fe–18Cr–10Ni–1Ti stainless steel. In addition, the oxidative portion in the wear mechanism for an oxynitrided surface is greater, which decreases the adhesive wear in such a friction pairVytauto Didžiojo universitetasŽemės ūkio akademij

Topography, hardness, elastic modulus and wear resistance of nitride coatings on titanium

The roughness, hardness and elastic modulus of the surface layers of c.p. titanium after thermodiffusion saturation with nitrogen at temperatures of α and β phase regions were investigated. It was established that the increasing temperature of gas nitriding provided a higher level of surface hardening (hardness, elastic modulus, depth of hardened layer) of the material but worsened the roughness of its surface. The tribological tests of hardened by nitriding c.p. titanium in pairs with 304L stainless steel showed lower friction coefficients in the period of rubbing, where the surface of the titanium was nitrided below the temperature of the transus temperatureVytauto Didžiojo universitetasŽemės ūkio akademij