To make the structure of cupolas meet the requirements of their optimum operation, the optimum design of melting zone diameter is shown by analysis of the internal relationship between the diameter and the melting intensity,and their variation.

Development of high melt strength polypropylene;

Increasing melt strength of polypropylene via reactive extrusion;

Study on preparation of polypropylene with high melt strength;

Experimental results indicate that(1) the predicted rules accord well with the actual ones;(2) the welding strength improves with the delay time of opening the valve gate;and(3) if the downstream valve gate does not open until the melt from the upstream valve gate passes it,the weldline strength is almost equal to that of the part in the location without weld line.

This paper introduces the technical theory of laser cladding and hardening, illustrates the corresponding developing trend at home and abroad, compares the new theory with the traditional one, and concludes the superiority of laser cladding.

These results were compared with chilled and WC coated cast irons,which illustrates that localized remelting hardening is a new surface trearment with full use of potential capacity of cast iron.