Microstructure Evaluation on Micro and Nano Slag Particles Reinforced AA7075 Composites

The research work was focused on utilization of solid industrial waste. In order to investigate the properties of Fe-Cr slag particulates strengthened AA7075 composites. In this paper addition of ferrochrome slag particles as reinforcement in AA 7075 alloy processed through stir casting technique. By varying size of ferrochrome slag particles were added to evaluate the size effects in the given alloy matrix. Prepared composites were subjected to heat treatment and evaluated for microstructure analysis. The results show that there is a uniform distribution of particles in the matrix and that there is a strong bond between the matrix and the reinforcement. Grain refinement in the alloy matrix is observed by inducing slag particles. Further nanocomposites show lower grain size values.

Influence of Micro and Nano Particles on Mechanical Behaviour of Slag Reinforced AA7075 Composites

Present studies are based on adding ferrochrome slag as reinforcement in AA 7075 alloy manufactured via the stir casting process. Two different slag particles are chosen; they are 36μm (Micro) and 68 nm (Nano). This was added to evaluate the size effects in the given alloy matrix. The composites were tested for unique microstructural properties and mechanical properties. The results Revealed uniform particle distribution within the matrix and good bonding between the matrix and the reinforcement. Better mechanical properties are obtained for both micro and nanocomposites than base alloy. This is further enhanced by ageing treatments. nanocomposites show superior mechanical properties than either alloy or micro composite. Interestingly, nanocomposite exhibits an increase in strength with good ductility; same is confirmed with fracture studies.

Ferrochrome slag aggregate: physical-chemical characteristics and potential use in lightly cemented road bases

Purpose Most developing countries simply dump ferrochrome slag as waste which occupies huge areas of useful land. The purpose of this study is to underscore the significance of reusing ferrochrome slag as a sustainable and eco-friendly road aggregate material, with the added benefits of preventing possible environmental pollution and promoting sustainable mining of non-renewable construction materials. Design/methodology/approach Physical-mechanical characteristics were investigated using various South African National Standards test procedures. Chemical and mineralogical characteristics were evaluated using the X-ray fluorescence and the X-ray diffraction techniques, respectively. The toxicity characteristic leaching procedure test was used to evaluate the slag’s environmental suitability. Using two cement types, cement proportions of 1%, 2% and 3% of the slag aggregate weight mixed with optimum moisture content of the non-treated compacted slag were used to make lightly cemented ferrochrome slag aggregate (LCFSA) composites, subsequently tested for compressive strength. Findings Ferrochrome slag aggregates have excellent physical-mechanical characteristics that conform to international specifications for use in road base construction. The slag can be classified as non-hazardous solid waste. However, in acidic environments, some toxic elements may leach from the slag and pollute the environment. Optimum cement contents of 2.3% (CEM II) and 2.6% (CEM VB) can be mixed with the slag to produce LCFSA for road bases. Originality/value No research was found in literature on the use of LCFSA in road bases. This research, therefore, presents new data on mix design and strength properties of LCFSA as well as some physical-chemical characteristics of coarse ferrochrome slag aggregate.

A Comparison in Metal Leachability Between Phosphoric Acid and Ascorbic Acid Stabilised Ferrochrome Slag

Ferrochrome (FeCr) slag was milled and stabilised with either ascorbic acid or phosphoric acid. The stabilised FeCr was then geopolymerised with 1 M KOH in order to obtain a monolith with at least an unconfined compressive strength of 1 MPa. The leachability of metals of the stabilised geopolymerised monoliths were then compared with the unstabilised geopolymerised monolith. Ascorbic acid stabilisation was only effective in Cr leaching reduction by 99.45% but was not effective on immobilisation of Fe, Zn, Ni and Mn. Ascorbic acid stabilisation was thought to proceed via the reduction of Cr(VI) species to insoluble Cr (III) species. Phosphate stabilisation reduced the leachability of Cr, Ni, Zn, Mn, Fe by 99.5%, 67.1%, 71.1%, 96.8% and 85.4% respectively. Phosphate stabilisation was thought to proceed via the formation of phosphate compounds of the metal ions in question. The phosphate stabilised FeCr slag leachability was within the allowable Toxicity Characteristic Leaching Procedure (TCLP) limits and its use is not detrimental to the environment.