This research examines the suitability of rice husk waste as an exothermic material for a riser sleeve for use in steel casting production. Exothermic sleeves are used in the steel casting process to compensate for shrinkage of the steel during solidification. Commonly, the exothermic sleeve consists of fuel materials, fillers, and binders. Rice husk waste has potential for use as a fuel material in the exothermic sleeve due to its high calorific value. For this study, rice husk waste was ground to gain a particle size of 60 mesh and then mixed with organic binders of 12wt%, 15wt%, and 18wt%. A H-sleeve was then formed by hand pressing, followed by drying. A series of quantitative tests were carried out to analyze the performance of the rice husk as an exothermic material. These include measurement of modulus extension factor (MEF) and the cooling rate of the steel casting within the liquidus-solidus temperature range. The test results show that the rice husk sleeve mixed with 12wt% of binder extended the solidification time from 273 seconds to up to 511 seconds within the desired temperature range. Furthermore, the best MEF of 1.69 was achieved using the rice husk riser sleeve. This meets the standard MEF value of an exothermic sleeve.

The Pulverizer pipe made of mild steel had erosion failure due to coal dust impacting, thus its service life also reduces. The ceramic coating overlay on the surface of mild steel is one of the appropiate ways to protect the mild steel from erosion. This research is aimed to perform a ceramic coating over the surface of the mild steel using a dipping method to improve its erosion resistance by using the alumina-phosphate ceramic coating. The coating layer is formed by the reaction between monoaluminum phosphate (MAP) as a binder and Al2O3 particles. It transforms into berlinite phase when heated at an elevated temperature. The observation is carried out with the variation of the MAP binder composition Al:P 25:75, 28:72, 30:70 and the Al2O3/MAP slurry is given at 40/60. Scanning electron microscopy is used to characterize the coating morphology. X-ray diffraction is applied to investigate the ceramic coating phases. The gas erosion jet measures erosion resistance of the ceramic coating. From the test result, it can be concluded that the binder composition influenced the erosion behaviour of alumina ceramic coating, the binder with Al:P (30:70) showed the erosion resistance increasing four times compared to the condition without coating.

This research is focused on the application of the Al2O3-phosphate ceramic coating on mild steel surface to protect mild steel from erosion in coal dust environment. Erosion resistance of mild steel could be improved by overlay it with SiC in the Al2O3-phosphate ceramic coating. As a filler, Al2O3 was mixed with 20%, 40%, and 60% SiC by using aluminium phosphate as a binder and heated at 220 °C for 5 hours. X-ray diffraction testing was conducted to observe the phase of Al2O3-SiC phosphate ceramic coating. Meanwhile, surface morphology and adhesion characteristic of Al2O3-SiC phosphate ceramic coating were analyzed by scanning electron microscope. To analyze the erosion resistance quantitatively solid particle impingement test by applying gas jets at the right angle (90°) against a sample surface has been conducted. The results showed that Al2O3-SiC phosphate ceramic coating is strongly bound to the mild steel surface without the presence of any void. The higher the SiC content can increase the ceramic coating density and its erosion resistance. The SiC 60% produces four times higher erosion resistance than uncoated mild steel. The material characterization of Al2O3-SiC phosphate ceramic coating proves that SiC gives a significant impact on the enhancement of erosion resistance of the Al2O3-SiC phosphate ceramic coating.

A low-high austempering process can be referred to as the application of undercooling condition in the austempering process of Austempered Ductile Iron (ADI). Undercooling condition promote more grain nucleation and producing finer grains with good mechanical properties. This study aims to investigate the influence of the first stage of lower temperature austempering holding time on its mechanical properties and find the best holding time which can produce the highest toughness of ADI materials. The experiment began with the heating of the nodular cast iron sample up to 927 °C and held for 120 minutes. Then it quenches to a liquid salt bath with a temperature of 260 °C as a lower temperature of the first austempering stage with a variation of holding time at 30, 60 and 90 minutes. Then it was transferred to a second salt bath medium of 400 °C as the second austempering stage with a holding time of 120 minutes then it was given the air cooling. The sample was tested by hardness, tensile, impact, and metallographic examination. The results show that the best toughness value in this research is obtained at 30 minutes holding time on first austempering stage with mechanical properties is tensile strength 1273 MPa, yield strength 1162 MPa, elongation 4,87% and impact value at 54.15 J. Value modulus of toughness is 5.93x107 J/m3.

This research aimed to improve the mechanical properties of NiCrMo alloyed steel casting, especially in terms of toughness. Toughness is a combination of tensile strength, yield strength, and elongation. The method used was a multi-heat treatment process involves normalizing, tempering, double tempering, and an additional intermediate process of quenching. The results obtained through the normalizing process followed by single quenching on oil media and double tempering (single quenching double tempering) produced the best-combined result of tensile strength, yield strength, and elongation. The modulus of toughness increased by up to 745 % compared to the as-cast condition from 20 N.mm/mm3 to 149 N.mm/mm3. The best mechanical properties were obtained from tempered martensite microstructure. It is free from rest martensite and secondary carbide.