JOM最新文献

Pigment production utilizes TiO₂-rich slags produced by the ilmenite smelting process which is sensitive to impurity levels in the titania slag. Thermodynamic analyses of ilmenite smelting were conducted to outline a path for process improvement. Specifically, the distribution of Ti and Fe, as well as a wide range of impurities, including V, Cr, Mn, Al, Si, Ca, Mg, P, and S, between the titania slag and molten iron were investigated. A comprehensive literature review was conducted to adequately ascertain the chemical compositions of ilmenite concentrates, which are among the most critical operational parameters in ilmenite smelting. Additionally, the quality requirements regarding impurity contents in the raw materials for TiO₂ pigment production were reviewed. The partition coefficients of elements between slag and metal determined as a function of process variables (i.e., oxygen partial pressure, temperature, and MgO/(Al₂O₃ + SiO₂) ratio) has been presented. Moreover, an in-depth analysis of the oxygen potentials during the ilmenite smelting process and the analysis of slag viscosity in corresponding process conditions have been shown. The analysis results are compared to the experimental data reported in the literature.

Electroless coating is such an area that has recently taken the research spotlight. Heat exchangers are the most used industrial equipment by chemical and mechanical firms. Of various other materials like copper, iron and carbon steel, it is considered that the structural units of these heat exchangers should be mild steel because the other metals are more porous in nature, encouraging corrosion, scaling and fouling. Mild steel is a revolutionary material that has a varied range of uses, from tiny needles to giant machinery. Easy market availability, material durability, great thermal efficiency and reasonable prices are the core reasons for this. However, the material has a few crucial disadvantages like corrosion, wear, fouling, pitting, etc. Electroless coating can be a good alternative to overcome these issues. These coatings can create novel nickel-based composite materials, of which Ni-P-Cu is the most common when the application demands the property of heat conduction. These coatings also provide great corrosion resistance. As our objective is the application of these composite coatings on heat exchangers, both corrosion and heat transfer properties have been demonstrated respectively in this study. The analysis has chosen electroless ENPC-coated mild steel at various concentrations of copper ranging from 0.2 g/l to 1.2 g/l. The surface morphology and elemental analysis have been explained using FESEM and EDX analysis. The material phase transformation has been observed using an XRD plot. The microhardness of the sample before and after the heat transfer study has been analysed and compared. The Tafel curve of the heated sample showed the increase of corrosion resistivity within the temperature range of 100°C to 400°C for an optimised coated sample ENPC-1, (i.e., electroless nickel phosphorous copper coating with copper concentration 1 g/l). A spray cooling setup built in house has been used to analyse the heat transfer mechanism. The cooling rate obtained for the ENPC-1 sample is around 25.2% more than in the previous studies on uncoated samples using base fluid (water).

The transformation of GCr15 bearing steel in carbide banding under both single hot field conditions and various parameters of pulsed magnetic field conditions was investigated in this paper. The effect of the pulsed magnetic field on carbide banding is elucidated in the research, and an innovative technique for mitigating carbide banding through the utilization of pulsed magnetic field is introduced. Comprehensive analyses of carbide banding distributions under different parameters were analyzed using optical microscopy, electron probe micro-analysis, electron backscatter diffraction and scanning electron microscopy. The findings reveal that the carbide banding grade is reduced from CZ7.6 to CZ7.1, and the average diameter of the carbide particles decreases from 667.51 nm to 287.37 nm under the application of the pulsed magnetic field. Thermodynamic analysis indicates a reduction in the nucleation potential barrier for carbide dissolution, and kinetic analysis shows an increase in the diffusion coefficient of carbide dissolution.

Hydroxyapatite (HA)-based materials are utilized as a bioactive ceramic for musculoskeletal reconstruction, owing to their chemical similarities to bone. However, they do not have any inherent antibacterial properties. Hence, post-surgical bacterial infection on HA scaffolds may cause osteomyelitis that needs to be rectified with costlier and more painful revision surgery. Our research aims to dope HA with transition metal oxides, such as ZnO and MgO, followed by loading tannic acid (TA) as an alternate antibacterial agent for various orthopedic and dental applications. The phase and microstructural investigation studies show no adverse effect as a result of doping. The combined effects of dopants and TA lead to ~ 98% antibacterial efficacy against S. aureus after 24 h of sample–bacterial interactions. The selected compositions do not show any adverse effects on the NIH3T3 cell line. In summary, our work proposes an alternate strategy to fabricate an antibacterial scaffold with TA-loaded ZnO and MgO-doped HA for various orthopedic and dental applications.