جستجوی مقالات مرتبط با کلیدواژه « تانتالوم » در نشریات گروه « مواد و متالورژی »

In this article, the effect of ion type on the transport properties of the structures whose common phases were created by the tantalum-based ion bombardment process has been investigated. The nitrogen ions used in the ion seeding process are considered with an energy of 30 kV and in different doses at ambient temperature. To study the morphology of the surfaces of ion bombarded thin layers, atomic force microscope (AFM) analysis was used and the amount Average roughness is determined. The results show that the common seasons produced by nitrogen ion bombardment have more effects on the transport characteristics. Also, the peak-to-valley ratio decreases. In addition, with the increase of the nitrogen ion dose, the current density has decreased as a function of the voltage, although this decrease is a direct result of the dispersion caused by the existence of unevenness, but the process of this decrease does not follow a specific order for different doses, example sample number one indicates a higher probability of passing. The results show that determining the amount of dose plays an important role in determining the amount of transport characteristics through uneven thin layers.

In this study, Ti-6A1-4V alloy was coated with a 200 nm thick tantalum nanolayer using physical vapor deposition method with electron beam in order to improve its surface and corrosion properties. The surface hardness and roughness of the control sample (Ti-6A1-4V) and those with tantalum coating (Ti-6Al-4V/Ta) were assessed. After coating, the surface hardness and roughness of the samples increased from 345 HV to 371 HV and from 0.055 µm to 0.107 µm, respectively. Moreover, the corrosion test in Hank's solution revealed that the corrosion current density of Ti-6Al-4V/Ta decreased from 1.9 µA/cm2 vs. 0.7 µA/cm2 for control sample. Following the corrosion test, the release rate of V, Al and Ti ions was examined. The results showed that the concentration of the released elements was halved after coating. Finally, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDS) were conducted to determine the phases, microstructures, and percentage of elements in the samples, respectively. The test results indicated that tantalum-coated Ti-6A1-4V alloy has desirable corrosion resistance and excellent mechanical properties and can thus be employed in dental and orthopedic implants.

Forming limit diagram (FLD) is an effective tool to evaluate the limiting strain in various conditions. In this study the formability of tantalum has been investigated and led to forming limit diagram of tantalum. For this propose three groups of tests has been carried out on the tantalum. At first، Erichsen test has been performed on sheets of tantalum to obtain the forming limit diagram (FLD). Then for evaluating the result of Erichsen test، compression test has been carried out. The obtained FLD of Erichsen test presented a good conformity with the FLD from compression test. In addition، the strain-hardening exponent، n، for tantalum has been obtained from tensile test. The n value from results of tensile test is close to the minimum point of forming limit diagram that indicate the strain-hardening exponent.