What is sintering in powder metallurgy process?
The operation of heating the green compact at high temperature in a controlled atmosphere (Reducing atmosphere which protects oxidation of metal powders). The Sintering increases the bond between the particles and therefore strengthens a powder metal compact. Sintering temperature and time of sintering depends on the type of powders and the strength required in a final product. The Sintering temperatures usually 0.6 to 0.8 times the melting point of powders.
Type of powder Sintering Temperature Time
Aluminium & Alloys 370 – 520 C 24 hrs
Copper, Brass, Bronze 700 – 900 C 30 Mins
Iron 1025 – 1200 C 30 Mins
Stainless Steel 1180 C 20 – 40 Mins
Tungsten Carbide 1480 C 20 – 40 Mins
Spark Plasma Sintering Mechanisms:
The process of simultaneous pressing & Sintering of metal powders by high energy electric spark. This spark is discharged from capacitor bank & removes the surface contaminants from powder particles. This cause the particles to form a solid cohesive mass. Immediately after spark, the current is continued for about 10 Seconds, with high temperature which further strengthens the bond used for sintering Aluminium, Copper, Iron and Stainless Steel.