TO DEVISE A PROCESSING ROUTE FOR MANUFACTURING VERY FINE-GRAINED WC-CO HARDMETALS THAT HAVE GOOD EDGE-RETENTION, HIGH REPRODUCIBILITY AND RELIABILITY.

FOR THE PURPOSE OF CUTTING CAST-IRON AND NON-METALLIC MATERIALS, HARDMETAL TOOLS ARE REQUIRED WITH GOOD EDGE-RETENTION, AND THIS PROPERTY IS ACHIEVED BY DECREASING THE WC GRAIN-SIZE TO REDUCE ATTRITION WEAR. ALTHOUGH VERY FINE-GRAINED WC POWDER IS CURRENTLY AVAILABLE, IT TENDS TO PRODUCE A WIDE GRAIN-SIZE DISTRIBUTION WHEN PROCESSES INTO A HARDMETAL, WITH A CONSEQUENT LARGE VARIABILITY IN PERFORMANCE.
THE EXPERIMENTAL APPROACH TO SOLVING THIS PROBLEM WILL BE TO STUDY THE SIZE DISTRIBUTION OF WC PARTICLES, THE SUBSTRUCTURE (DISLOCATION) OF THE POWDERS, AND THE BINDER-METAL COMPOSITION AT ALL STAGES OF THE PROCESSING ROUTE, SINCE THESE PARAMETERS WILL HAVE AN IMPORTANT EFFECTS ON THE SINTERING KINETICS AND THE FINAL MICROSTRUCTURE. IT IS ENVISAGED THAT BY IDENTIFYING THE MOST FAVOURABLE POWDER SUBSTRUCTURE AND WC PARTICLE SIZE DISTRIBUTION FOR RETAINING A VERY FINE UNIFORM GRAIN SIZE, IT WILL BE POSSIBLE TO DEVISE A SUITABLE MIXING AND MILLING PROCEDURE, WITH POSSIBLE INTERMEDIATE ANNEALING OF THE POWDERS, AND ADDITION OF GRAIN-GROWTH-INHIBITORS SUCH AS CR AND V.
THE WORK WILL BE PERFORMED IN THREE STAGES:
- EXAMINATION AND TESTING OF AVAILABLE VERY FINE-GRAINED HARDMETALS AND POWDERS;
- INVESTIGATION OF THE EFFECTS OF VARYING THE PROCESSING TREATMENT ON THE MICROSTRUCTURE OF THE POWDER, AND ON THE MICROSTRUCTURE, MECHANICAL PROPERTIES, AND WEAR PERFORMANCE OF THE MICROSTRUCTURE, MECHANICAL PROPERTIES, AND WEAR PERFORMANCE OF THE SINTERED PRODUCT;
- PERFORMANCE TESTING OF PRODUCTS.
THE RESULTS WILL APPLY MAINLY TO TOOLS USED IN CUTTING AND FORMING NON-METALLIC MATERIALS, WHERE THERE WILL BE EXTENDED SERVICE LIFE AND REDUCED DOWN-TIME FOR REPLACING WORN OUT AND BROKEN TOOLS. THERE WILL ALSO BE APPLICATIONS IN AUTOMATIC MACHINE-TOOL OPERATIONS, WHERE AN IMPROVEMENT IN RELIABILITY WOULD ENABLE HARMETALS TO REPLACE HIGH SPEED STEELS WITH RESULTANT INCREASE IN THE NUMBER OF ITEMS MACHINED PER CUTTING EDGE.
THIS PROJECT WILL BE CARRIED OUT IN FULL COLLABORATION WITH THE NATIONAL PHYSICAL LABORATORY, TEDDINGTON, UK, (SUM-038-UK).