Ahmad Aswad Mahaidin

Physical and Mechanical Properties of WC-Co Submicron Powders Using P/M Technique

The properties of WC-Co are greatly improved with the use of submicron powders. However, grain growth tends to occur during the sintering process which causes the properties to deteriorate to some extent. Free carbon and vanadium carbide are added in this study to serve as grain growth inhibitor. The effect of these two materials is evaluated based on WC-Co properties. In this work, the powders are mixed together via wet mixing process, compacted and undergo cold-isostatic pressing (CIP) before the samples are sintered in the temperature range of 1350-1450°C under nitrogen-based atmosphere. The physical and mechanical properties of the WC-Co sintered powders were analysed. Based on the work done, the WC-Co-C has a better properties compared to WC-Co-VC.

Rheological Study of a Copper Feedstock

MIM technique is described in which allows for the production of highly porous metallic foams with porosity levels up to 90%. It makes use of the pressure built up by the decomposition of a foaming agent which is incorporated in a foamable precursor copper material obtained by powder compaction. A suitable behaviors feedstock that refers to its rheological is one of the key factors to ensure the successful of MIM technique and to predict failure, whether due to the binder component and compositions, powder loading or unsuitable process parameters. Potassium carbonate and polyethylene is added and were mixed homogeneously to form a copper feedstock. The rheological results in term of shear rate, shear stress, viscosity, melting rate and softening temperature which related to pseduoplastic behaviors have been conducted using a capillary rheometer (CFT-500D, Shimadzu) at various temperature and loads. The result has indicated that the viscosity of the feedstock is decreased with increasing shear rate thus proved the feedstock to be pseudoplastic.

Mechanical Properties and Microstructures of WC-Co Cutting Tool Inserts with Addition of VC

The mechanical properties and microstructures of WC-Co are highly dependent on its cobalt content, grain size of the WC particles and sintering temperature. In this work, the effect of addition of VC powder on the mechanical properties and microstructures during the consolidation of process will be investigated. The WC-Co and WC-Co-VC cutting tool inserts were fabricated using powder metallurgy route. The powders were wet mixed with heptane in turbula mixer for three hours, dried and then granulated. The mixed powders were uniaxially pressed at a pressure of 625 MPa and cold-isostatic pressed at a pressure of 200 MPa. The compacted samples were sintered in the temperature range of 1350 1450°C under nitrogen-based atmosphere. The mechanical properties of the samples are analyzed using Vickers microhardness tester, universal tensile machine and the microstructures of the sintered sample were observed using field emission scanning electron microscope. Microstructural examinations showed that VC particle is good as grain growth inhibitor as a result of good precipitation of VC in WC grain boundaries. However the addition of VC in WC-Co hardmetal resulted in the reduction of hardness and transverse rupture stress due to increase of pores in the microstructures of sintered samples.

Effect of Heat Treatment Process of Sintered M3/2 High Speed Steel Parts

Dry machining is one of the ways to achieve a reduction of cooling lubricants, as well as reduced environmental pollution and lower health risk to workers. This leads to higher mechanical and thermal loading on cutting edges. The adaptation of cutting tools to the requirements of dry machining includes the optimisation of manufacturing technologies, the development of cutting materials of sufficient toughness and high hot hardness, the design of tool geometries as well as the coating of tools [.

Effect of Compaction Load and Heat Treatment in Manufacturing of HSS Cutting Inserts under Nitrogen-Based Atmosphere

High speed steels (HSS) is used in manufacturing of cutting tools and wear components because of its superior mechanical properties and wear resistance. In this study, the optimization manufacturing parameters such as compacting pressure and heat treatment temperatures will be studied. The powder of HSS and iron phosphorous were dryly mixed for 30 minutes. The mixed powders were compacted at the pressure in the range of 300- 632 MPa, sintered in the temperature range of 1100 - 1225 °C, annealed in the temperature range of 1100 - 1175 °C and tempered in the temperature range of 500 - 600 °C. The mechanical properties of the samples are analyzed using Vicker’s microhardness tester, universal tensile machine and the microstructures of the sintered sample were observed using field emission scanning electron microscope. Test results revealed that the optimum manufacturing parameters are as follows; (i) compacting pressure of 632 MPa, (ii) sintering temperature of 1200°C, (iii) annealing temperature of 1175 °C, (iv) tempering temperature of 500 °C.