Microstructural characterization, mechanical and tribological properties of ZC71 hybrid composite reinforced with SiC and MWCNT

In the present study, the influences of different SiC addition, MWCNTs and various SiC particle sizes on the structural, mechanical and tribological properties of ZC71 alloys were studied. The results revealed that the proper amount/size of SiC particles with the addition of MWCNTs had a considerable effect on the microstructural alteration, and mechanical and tribological properties of the ZC71 alloy. The Vickers hardness values of the ZC71 alloy improved with the addition of MWCNT and SiC. The UTS (216 MPa) and El.% (6.95 %) were achieved in the ZC71-5%SiC(15µm)-0.5%MWCNT. The cast ZC71 alloy showed brittle fracture with some quasi-cleavage characterizations. However, by adding 5% SiC (15 µm) and 0.5% MWCNT, the fracture mode changed to ductile fracture. The wear results showed that the ZC71-5%SiC-0.5%MWCNT hybrid composite had the highest wear resistance with the lowest friction coefficient and wear rate. Examination on the worn surface of the ZC71-5%SiC-0.5%MWCNT hybrid composite showed mild abrasion as the governing wear mechanism

Rheological and Thermal Characterization of AISI 4605 Low‑Alloy Steel Feedstock for Metal Injection Molding Process

In this study, rheological and thermal decomposition behavior of AISI 4605 MIM feedstock investigated using capillary and thermogravimetric analysis. For this purpose and in order to find the critical solids loading, the feedstock was prepared by compounding AISI 4605 micro powder (similar to 4 mu m) with an adopted multi-component wax-based binder system at various powder loadings (53-61 vol%). After preparing the feedstock with optimal solids loading, fundamental rheological characteristics of homogenized feedstock, including flow behavior index (n), flow activation energy (E), and general moldability index (alpha(stv)) were studied. Furthermore, thermal analysis of feedstock, including apparent debinding activation energy and master decomposition curve was investigated. The results showed that critical solids loading of feedstock is around 58 vol%. The flow behavior index of developed feedstock was acceptable, since it came out to be less than one. Also, flow activation energy which shows the sensitivity of material to temperature changes, came out to be 70.406 kJ/mol. Using these two parameters, general moldability index was calculated to be 2.3147E-06. Finally, the master decomposition curve of feedstock was constructed based on calculated apparent debinding activation energy and verified using decomposition curves at different heating rates of 2, 5 and 10 degrees C/min. Graphic11Nsciescopuskc

The effect of debinding and sintering parameters on the mechanical and microstructural properties of Fe-2Ni metal injection molded compacts

This paper investigates the effect of debinding and sintering parameters on the density, ultimate tensile strength (UTS), hardness and grain size of the Fe-2Ni MIM compact. For this purpose, a wax-based binder system containing PE, PP, PW and SA was adopted for developing the feedstock. After optimizing the feedstock powder loading based on the critical solids loading and studying the homogeneity of feedstock, green parts were injected. The samples were then immersed in the n-hexane solution for different times to investigate the effect of debinding time on the weight loss of binder system. After observing the samples shrinkage behavior, sintering temperatures were selected and the samples were sintered at temperatures of 1050, 1125, 1200, 1275 and 1350 degrees C. Finally, the microstructure, density and hardness of the sintered samples were evaluated and the UTS of the samples was measured using the DIC technique. The results showed that immersion of samples for 12 h in n-hexane with 50 degrees C temperature applied as optimum parameters for solvent debinding. In addition, appropriate thermal debinding cycle was designed through the TGA analysis to produce flawless samples. It was observed that the density increases with the sintering temperature increasing, until where in the temperature of 1350 degrees C the relative density was 97.2%. UTS and hardness values of the sintered samples increased to (similar to 548 MPa) and (similar to 144 HV) for the sintered specimen at 1275 degrees C and decreased at higher temperature. This phenomenon relates to the substantial grain growth in the sintered sample at 1350 degrees C, as proved by the results of EBSD analysis. Finally, proper sintering condition for Fe-2Ni samples derived through the density, UTS, hardness and microstructural evaluations, so that sintering of the samples at 1275 degrees C under hydrogen atmosphere showed the optimum condition due to an excellent balance between the mechanical properties and grain size in the samples.11Nscopu