Suraya Mohd Tahir

Deformation and Mechanical Characteristics of Compacted Binary Mixtures of Plastic (Microcrystalline Cellulose), Elastic (Sodium Starch Glycolate), and Brittle (Lactose Monohydrate) Pharmaceutical Excipients

This work studies the tensile strength, coherence, elastic, and plastic energy of single and bi-component compacted tablets consisting of (i) microcrystalline cellulose (MCC) PH 102 as a plastic material, (ii) (SSG) as an elastic material, and (iii) alpha lactose monohydrate as a brittle material by direct compression. Compacted tablets were studied with various mass ratios formed at an ultimate compaction stress of 150 MPa. The loading and unloading stages of the compaction process for the single and binary tablets were evaluated based on the energies derived from the force-displacement data obtained. The resulting tablet quality was measured in terms of the tensile strength. Material that exhibit predominantly plastic deformation (MCC) shows a dominant property over elastically deforming sodium starch glycolate (SSG) and brittle (lactose) materials during the loading and unloading stages of the compaction process. In conclusion, the tensile strength of the formed tablets depends directly on the plastic energy and indirectly on the elastic energy and is negatively affected by the presence of a brittle material.

Compaction of Sweet Potato (Ipomoea batatas L.) and Stevia Rebaudiana Food Powders

This study has been conducted to evaluate the suitability of sweet potato and Stevia powders as tablets in terms of their compaction behavior and mechanical strength in comparison to an established pharmaceutical binder; microcrystalline cellulose. The results indicated that the behavior of the material during compression, namely, the plastic and elastic deformations influences the final tablet mechanical strength. Relatively high plastic deformation of a material during compression enhances the contact area for interparticulate bonding, thus, producing a mechanically strong tablet. It was observed that the compaction of stevia powder produces a mechanically stronger tablet in comparison to the sweet potato tablet.

Simulation of Crack Propagation in Metal Powder Compaction

This paper presents the fracture criterion of metal powder compact and simulation of the crack initiation and propagation during cold compaction process. Based on the fracture criterion of rock in compression, a displacement-based finite element model has been developed to analyze fracture initiation and crack growth in iron powder compact. Estimation of fracture toughness variation with relative density is established in order to provide the fracture parameter as compaction proceeds. A finite element model with adaptive remeshing technique is used to accommodate changes in geometry during the compaction and fracture process. Friction between crack faces is modelled using the six-node isoparametric interface elements. The shear stress and relative density distributions of the iron compact with predicted crack growth are presented, where the effects of different loading conditions are presented for comparison purposes.

Mechanical properties of WC-based hardmetals bonded with iron alloys – a review

Growing concerns over the use of cobalt as binder for WC-based hardmetals has directed research efforts towards finding a suitable alternative binder offering comparable or even superior properties than those found in WC–Co hardmetals. Complete substitution of cobalt by iron alloys has been extensively explored in several studies with significant improvements in mechanical properties of WC bonded with Fe alloys when carbon content addition is strictly controlled in powder composition. Asides from the commonly studied hardness and fracture toughness properties, transverse rupture strength property of this composites has also been observed to hold future promise with further development in the microstructural parameters such as porosity during sintering. This article reviews the progress in the mechanical properties of WC–Fe alloys hardmetals.

The Effect of Commercial Rice Husk Ash Additives on the Porosity, Mechanical Properties, and Microstructure of Alumina Ceramics

A porous ceramic is made from composite materials which consist of alumina and commercial rice husk ash. This type of ceramics is obtained by mixing the commercial rice husk ash as a source of silica (SiO2) and a pore forming agent with alumina (Al2O3) powder. To obtain this type of ceramic, a solid-state technique is used with sintering at high temperature. This study also investigated the effects of the rice husk ash ratios on the mechanical properties, porosity, and microstructure. The results showed that, by increasing the content of the rice husk ash from 10 to 50 wt%, there is an increase in the porosity from 42.92% to 49.04%, while the mechanical properties decreased initially followed by an increase at 30 wt% and 50 wt%; the hardness at 20 wt% of the ash content was recorded at 101.90 HV1. When the ash content was increased to 30 wt% and 50 wt%, the hardness was raised to 150.92 HV1 and 158.93 HV1, respectively. The findings also revealed that the tensile and compressive strengths experienced a decrease at 10 wt% of the ash content and after that increase at 30 wt% and 50 wt% of rice husk ash. XRD analysis found multiple phases of ceramic formation after sintering for the different rice husk ash content.

Effect of Particle Size on Direct Compaction of Urea Fertilizer

The effect of particle size on compaction properties and characteristics of urea tablets manufactured from available urea granules (TG tablets) and ground urea powders (TP tablets) was investigated. The compaction properties, namely, plastic work, elastic work, friction work, and maximum ejection pressure were analyzed from the force-displacement profile of the compaction process. Five applied pressures ranging between 37.67 MPa and 188.35 MPa were used to compact the materials using a universal testing machine. Characteristics of the tablets tested were mechanical strength and the release of ammonium ion through dissolution test. The results demonstrated that TG tablets underwent high plastic work and elastic work but low friction work compared to the TP tablets. TG tablets released lower amount of ammonium ion compared to the TP tablets at almost all applied pressures, except at 75.34 MPa. This study provides a valuable data for evaluating the behavior of urea in the form of granules and powders during the compaction process as well as the suitability in choosing the form of raw material for the production of urea tablets.

Factors Affecting the Porosity and Mechanical Properties of Porous Ceramic Composite Materials

In recent years, there has been an increasing interest in the study of porous ceramic composite materials. There are many products made of porous ceramic, such as membranes, catalytic substrates, filters, and others. This is due to their excellent properties in terms of high temperature stability, high permeability, excellent catalytic activity, and low bulk density. The purpose of this article is to review in detail the factors affecting the porosity of ceramic material, such as pore forming agents, the mechanical properties, and methods available to strengthen the material, such as sintering temperature, ceramic additives, and metal particle as additives and coating. Machining is also a concern regarding products made of ceramic materials since it is brittle in nature. Parameters optimized to improve machinability for ease of machining process were also discussed to address this concern.

Effect of Filler Loading and Coupling Agent on Tensile and Impact Properties of Polypropylene with Oil Palm Ash Composites

The purpose of this research is to investigate the effect of filler loading and using coupling agent on tensile and impact properties of thermoplastic polypropylene composite with oil palm ash (OPA) powder. This research is intended to discover the dependant various effect of loading percentage weight of filler OPA and coupling agent maleated anhydrate polypropilene (MAPP) on tensile and impact properties of thermoplastic composite. This materials is weighed as OPA loading percentage 0%, 1%, 3%, 5% and 7% while the loading percentage of coupling agent MAPP 0%, 3%, 6%, 10% and 12% affect the mechanical properties of thermoplastic composite. Mixture process has been carried out using double-screwed extruder machine at constant speed and temperature,while board manufacturing of PP/OPA composite are made used hot press and cold press machine. Loading OPA and MAPP effect on polypropylene composite were tested through mechanical testing , specifically for tensile and impact properties. All testing methods are predicated from ASTMs standard (American Society for Testing and Material). Results showed lower OPA content and highest MAPP in ratio giving the highest tensile and impact strength of the composite.

Effect of Cu Metal of Nanoscale Particle Size on the Porosity and Mechanical Properties of Porous Alumina Ceramics using Yeast as a Pore Agent

The main goal of this study is to determine the effect of the addition of Cu metal of nanoscale particle on the mechanical properties and porosity of porous alumina ceramics. Porous alumina reinforced ceramics were prepared using nanoscale Cu metal particles as their strengthening phase. Solid state and sacrificial techniques were used to prepare the porous alumina reinforced ceramics. A FESEM was used to analyse the microstructure. Different ratios of Cu metal were added (3 wt%, 6 wt%, 9 wt% and 12 wt% Cu) at different ratios of yeast used as a pore agent. The results indicated that with increasing the ratios of Cu metal, the porosity decreased and the mechanical properties increased. The increase in the mechanical properties could be attributed to the decrease in the porosity and the toughening mechanism of porous alumina ceramics. Some potential applications include, filtration, thermal and purging of gas.

Sintering Behaviour of Cemented Tungsten Carbide and Steel Bilayer

The target of processing bimaterial components by cost effective powder metallurgy is to combine unique properties from different parts of the component. Differential shrinkage rate and more often, radial mismatch which is more consistent in bilayer owing to sintering conditions (time, rate, temperature etc.) is known to compromise the interfacial bond strength and integrity of these components. Therefore, the aim of this study is to analyze the sintering compatibility and evaluate the mismatch strain in cemented tungsten carbide (WC-Fe-C) and steel (Fe-W-C) bilayer processed through powder metallurgy (PM) to combine the hardness and toughness properties applicable in machining industries for drilling tools. Through geometrical measurement, mismatch strain rate between layers at different sintering temperatures was calculated and a value as low as 13.7% was observed at the interfacial zone of MC–0.2 specimen sintered at 1280°C indicating a stronger bond between layers compared to those sintered at 1290°C and 1295°C where a huge mismatch was found increasing the tendency for delamination.