Papers by Author: Zainul Huda

Abstract: This paper presents a case study of ASME SA213 type-T22 alloy steel superheater tube that failed in a boiler of a power plant. The failed superheater tube was investigated by visual examination, metallography, optical microscopy, electron fractography, and hardness testing. Microscopic examinations revealed inclusion, pre-existing micro-cracks and cementite precipitates at the grain boundaries in the microstructure; which were thought to be one of the major causes of failure of the superheater tube. Another major cause failure of boiler type T-22 was found to be creep failure because the boiler had been under use for a long time (36573 hours) at high steam temperature of around 420 °C with 130 bar pressure. Finally, recommendations have been suggested to improve the material characteristics and properties of the superheater tube for application in boiler of the power plant.

Abstract: This review paper presents a fail-safe approach in designing biomaterials against wear for application in an artificial total hip replacement in view of the recent advances in orthopedic bioengineering materials. It has been established that substantially different alloys should be used for minimizing wear in bearing surfaces. Frictional forces at these rubbing counter-faces must be minimized to prevent loosening of the femoral stem and acetabular socket assembly from their positions secured by the fixation agent. A comparative analysis of various wear-resistant biomaterials resulted in the lowest production of wear particles in a total hip where a ceramic socket articulates against the ceramic ball: it produces only 0.004 cubic millimeters of ceramic wear particles. Surface modification, through the application of coatings, offers the potential to reduce the wear rate without compromising the bulk mechanical behavior of the implant material. These hard coatings were found to include diamond-like carbon, amorphous diamond, and titanium nitride.

Abstract: The current literature reports the quantitative analysis of the kinetics of grain growth influenced by second-phase particle mechanisms for a powder metallurgy nickel-base superalloy: APK-6. Annealing treatments in the superalloy are shown to involve coarsening/dissolution of γ’ particles, and these particles mechanisms are shown to influence the kinetics of grain growth. The grain-growth exponent, n, is computed, and the γ’-solvus temperature of the superalloy is determined to lie between 220 and 270 oC. The kinetic data is interpreted to establish dependence of γ’ particles coarsening/dissolution mechanisms, grain size, γ’-solvus temperature, and annealing time and temperature on the rates of grain growth in the superalloy.