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.

In this work, the effects of porosity and different particle sizes of pore-forming agent on the mechanical properties of porous alumina ceramics have been reported. Different grades of porous alumina ceramics were developed using corn cob (CC) of different weight contents (5, 10, 15, and 20 wt%) and particle sizes (<63 µm, 63-125 µm and 125-250 µm) as the pore-forming agent. Experimental results showed that total porosity and pore cavity size of the porous alumina ceramics increased with rising addition of CC pore former. Total porosity increased with increasing particle size of CC with the Al 2 O 3-<63 CC 5 sample exhibiting the lowest total porosity of 41.3 vol% while the highest total porosity of 68.1 vol% was exhibited by the Al 2 O 3-125-250 CC 20. The particle size effect of CC on the mechanical properties revealed that diametral tensile strength and hardness of the porous alumina ceramics deteriorated with increasing particle size of CC pore former. The Al 2 O 3-<63 CC 5 sample exhibited the highest diametral tensile strength and hardness of 25.1 MPa and 768.2 HV, respectively, while Al 2 O 3-125-250 CC 20 exhibited the lowest values of 1.1 MPa and 35.9 HV. Overall, porous alumina ceramics with the smallest pore sizes under each particle size category exhibited superior mechanical properties in their respective categories.

No abstract

No abstract

No abstract