The present paper is related to the conversion of Ti–6Al–4V chips into powder and investigates the usability of the produced powder in powder metallurgy applications. In this regard, a disc-milling process was appli...The present paper is related to the conversion of Ti–6Al–4V chips into powder and investigates the usability of the produced powder in powder metallurgy applications. In this regard, a disc-milling process was applied to Ti–6Al–4V chips and the obtained powder was subsequently compacted. The compacted samples were sintered by the sinter hot isostatic pressing (sinter-HIP) method at 1200°C under high vacuum, their mechanical properties and microstructure were investigated and compared with those of commercial powder compacts subjected to the same preparation processes. The results showed that the produced powder exhibits greater flowability and higher apparent density than the commercial powder. However, the sintered products prepared from the commercial powder exhibited a higher relative density, lower porosity, and, as a result, greater flexural strength compared with the sintered compacts prepared from the produced powder. In addition, transgranular fracture was greater in the sintered products of the commercial powder. The microstructural studies revealed that the sintered products made from both the commercial and the produced powders consisted of α- and β-phase but contained more α-phase. All of the examined properties were found to be substantially affected by the particle size of the powders.展开更多
This study aims to draw an exact boundary for microstructural and mechanical behaviors in terms of pulsed plasma nitriding conditions.The pulsed plasma nitriding treatment was applied to AISI 304 austenitic stainless ...This study aims to draw an exact boundary for microstructural and mechanical behaviors in terms of pulsed plasma nitriding conditions.The pulsed plasma nitriding treatment was applied to AISI 304 austenitic stainless steel at different temperatures and durations.Results reveal that nitriding depth increased as process temperature and duration increase.The nitriding depth remarkably increased at 475℃for 8 h and at 550℃for 4 h.An austenite structure was transformed into a metastable nitrogen-oversaturated body-centered tetragonal expanded austenite(S-phase)during low-temperature plasma nitriding.The S-phase was converted to CrN precipitation at 475℃for 8 h and at 550℃for 4 h.Surface hardness and fatigue limit increased through plasma nitriding regardless of process conditions.The best surface hardness and fatigue limit were obtained at 550℃for 4 h because of the occurrence of CrN precipitation.展开更多
Objective To study the effects of radiation emitted by mobile phones on bone strength and caffeic acid phenethyl ester （CAPE） on the changes induced by radiation. Methods Forty-eight Sprague-Dawley rats were divided...Objective To study the effects of radiation emitted by mobile phones on bone strength and caffeic acid phenethyl ester （CAPE） on the changes induced by radiation. Methods Forty-eight Sprague-Dawley rats were divided into five groups. Rats in the control group （first group） were left within the experimental setup for 30 min/day for 28 days without radiation exposure. Nine hundred MHz radiation group was broke down into 2 subgroups （group 1/2）. Both subgroups were exposed to radiation for 28 days （30 min/day）. The next group was also divided into 2 subgroups （group 3/4）. Each was exposed to 1800 MHz of radiation for 28 days （30 mirdday）. The third and fifth groups were also treated with CAPE for 28 days. Treatment groups received ip caffeic acid phenethyl ester （10 ktmol/kg per day） before radiation session. Bone fracture was analyzed. Results Breaking force, bending strength, and total fracture energy decreased in the irradiated groups but increased in the treatment groups. Conclusion Radiation and CAPE can significantly improve bone.展开更多
基金financially supported by Faculty Member Training Program funded by Council of Higher Education Turkey [OYP-05276-DR-12]
文摘The present paper is related to the conversion of Ti–6Al–4V chips into powder and investigates the usability of the produced powder in powder metallurgy applications. In this regard, a disc-milling process was applied to Ti–6Al–4V chips and the obtained powder was subsequently compacted. The compacted samples were sintered by the sinter hot isostatic pressing (sinter-HIP) method at 1200°C under high vacuum, their mechanical properties and microstructure were investigated and compared with those of commercial powder compacts subjected to the same preparation processes. The results showed that the produced powder exhibits greater flowability and higher apparent density than the commercial powder. However, the sintered products prepared from the commercial powder exhibited a higher relative density, lower porosity, and, as a result, greater flexural strength compared with the sintered compacts prepared from the produced powder. In addition, transgranular fracture was greater in the sintered products of the commercial powder. The microstructural studies revealed that the sintered products made from both the commercial and the produced powders consisted of α- and β-phase but contained more α-phase. All of the examined properties were found to be substantially affected by the particle size of the powders.
基金the Scientific and Technological Research Council of Turkey(TUBITAK)for the support of this study(Grant No:215M134)。
文摘This study aims to draw an exact boundary for microstructural and mechanical behaviors in terms of pulsed plasma nitriding conditions.The pulsed plasma nitriding treatment was applied to AISI 304 austenitic stainless steel at different temperatures and durations.Results reveal that nitriding depth increased as process temperature and duration increase.The nitriding depth remarkably increased at 475℃for 8 h and at 550℃for 4 h.An austenite structure was transformed into a metastable nitrogen-oversaturated body-centered tetragonal expanded austenite(S-phase)during low-temperature plasma nitriding.The S-phase was converted to CrN precipitation at 475℃for 8 h and at 550℃for 4 h.Surface hardness and fatigue limit increased through plasma nitriding regardless of process conditions.The best surface hardness and fatigue limit were obtained at 550℃for 4 h because of the occurrence of CrN precipitation.
文摘Objective To study the effects of radiation emitted by mobile phones on bone strength and caffeic acid phenethyl ester （CAPE） on the changes induced by radiation. Methods Forty-eight Sprague-Dawley rats were divided into five groups. Rats in the control group （first group） were left within the experimental setup for 30 min/day for 28 days without radiation exposure. Nine hundred MHz radiation group was broke down into 2 subgroups （group 1/2）. Both subgroups were exposed to radiation for 28 days （30 min/day）. The next group was also divided into 2 subgroups （group 3/4）. Each was exposed to 1800 MHz of radiation for 28 days （30 mirdday）. The third and fifth groups were also treated with CAPE for 28 days. Treatment groups received ip caffeic acid phenethyl ester （10 ktmol/kg per day） before radiation session. Bone fracture was analyzed. Results Breaking force, bending strength, and total fracture energy decreased in the irradiated groups but increased in the treatment groups. Conclusion Radiation and CAPE can significantly improve bone.
