Effect of Manganese Additions and Wear Parameter on the Tribological Behaviour of NFGrey (8) Cast Iron

The effect of manganese and wear parameter on the abrasive wear behaviour of NFGREY8 cast iron composition under dry lubrication conditions was investigated. The wear parameters studied are sliding speed, applied load, time and percentage of ferro-manganese additions. The experimental data were taken in a controlled way. Scanning electron microscope was used to examine the morphology of the samples. The results from linear regression equation and analysis of variances (ANOVA) shows that manganese additions, load and speed variable are more pronounced on the wear behaviour of the NFGrey (8) cast iron. The result showed that the additions of the 75 % ferro manganese grade decreases the carbon equivalent CE and fortify the matrix with the formation of tough (FeMn)3C inter-metallic leading to increased wear resistance of the examined composition

Effect of heat treatment on wear resistance of a grinding plate

The effects of heat treatment on the hardness and by extension the wear resistance of locally produced grinding plate of known composition were investigated. Specimens were prepared from the grinding plate and were heat treated at 840°C, 860°C and 880°C and quenched at different rate. Some of the specimens were quenched in water and palm oil, while some of the quenched specimens were tempered at 200°C. The results obtained were corroborated with the microstructure of the specimens examined under an optical microscope. The hardness values of the grinding plate specimens quenched in various media increased with increased heat treatment temperatures, and are higher than that of the as-cast specimen. Water quenched tempered specimens (WT) displayed higher hardness values than the as-cast, whereas oil quenched tempered specimens (OT) possessed lower hardness values. The presence of carbide was evident on the micrographs of the water quenched specimens at all the exposure temperatures, which corroborated the observed increased in the hardness values with increased heat treatment temperatures. However, there was significant reduction in the hardness value of the water quenched tempered specimens compared with the quenched specimens, which indicates a significant improvement in toughness. Thus, water quenched and tempered specimen with relatively high hardness value and improved toughness, will be suitable for use as grinding plate because of its relatively better wear resistance. The hardness of the specimens was found to depend on the formation of carbide precipitates within the matrix structure. There is also possibility of production of structure consisting of graphite embedded in a martensitic matrix through the heat treatment.Keyword: carbide, heat treatment, hardness, microstructure, wear resistanc

Review on Oxide Formation and Aluminum Recovery Mechanism during Secondary Smelting

The remelting, refining, and casting process of aluminum alloys often generate aluminum dross containing primarily oxides and nitrides of aluminum and entrapped metallic aluminum at the surface of the molten metal as a result of reactions within the furnace atmosphere at elevated temperatures. The handling of dross is an expensive but necessary activity during aluminum smelting. Furthermore, the amorphous Al2O3 oxide film formed on the pure molten aluminum surface due to the liquid metal randomly distributed atoms is impermeable to the diffusion of aluminum metal and oxygen. In amorphous materials, there is a low mobility of the charge carriers and an absence of preferred diffusion paths. This film can transform to crystalline Al2O3 by nucleation and grows with time and opportunity. This review discusses the mechanism of oxide formation and the aluminum metal recovery processes

Synthesis and graphitization of resole resins by ferrocene

Commercial (Rs) and laboratory synthesized resoles (LSRs) containing 3–5 wt% ferrocene have been used to study the development of thermosetting resin compositions as binder materials for carbon-containing refractories (CCRs) production. The LSRs were developed based on formaldehyde to phenol 1.5 mol.% (1.5Rs) and 2.0 mol.% (2Rs). Microstructure and oxidation resistance of carbons derived from plain and modified resins have been compared. Chemical structure of the resins was studied using Fourier Transform InfraRed-Attenuated Total Reflection (FTIR-ATR) spectroscopy. X-ray Photoelectron spectroscopy was used to examine chemical changes during heat treatment of the modified products. Flow behavior of plain and formulated resins has been measured under isothermal condition. Rheology measurement results show that the selected amount of ferrocene did not affect the resin near-Newtonian fluid behavior and processability during refractory production. X-ray diffraction (XRD) analysis and transmission Electron Microscope (TEM) were used to characterize the derived carbon samples after thermal treatment of the resins. The results demonstrate that ferrocene is an excellent additive for crystallizing resoles carbon. The presence of fringes in TEM images indicates the graphitized carbon microstructure. The carbon reactivity in an oxidizing environment was also determined via thermogravimetric analyzer (TGA). Several factors, such as bond strength and atoms arrangement, have been found to control the carbonized modified-resin oxidation resistance. Keywords: Resole resins, Synthesis, Graphitization, Microstructure, Oxidation resistanc