Application of U-FAST Technology in Sintering of Submicron WC-Co Carbides

Spark Plasma Sintering of Fine-Grained WC-Co Composites

Cemented carbides WC-Co are one of the basic tool materials. They constitute over half of the currently used tools intended for machining. The main advantages of WC-Co cemented carbides are high hardness and abrasion resistance. The properties of WC-Co sinters depend mainly on the content of the binding phase, the sintering method and the grain size of the powder from which the sinters were made. The aim of this study was to produce fine-grained WC-Co composites using SPS (spark plasma sintering) technology, as well as examine the effect of the applied technology on the basic properties of WC-Co sinters: microstructure, hardness, phase composition, compaction degree and tribological properties. In the processes carried out, no additives affecting the reduction in grain growth were used. Sintering was conducted at a temperature of 1200 °C with a holding time of 10 min. The process occurred under a load of 100 MPa. Finally, the samples were cooled in a vacuum of 10-6 mbar. We measured the hardness using a Vickers hardness tester. We took hardness measurements along the diameter of the sintered samples. In order to ascertain the fracture toughness (KIC), we measured the radial crack length around the Vickers indentation and applied Shetty's formula. The tribological tests were carried out with a tribotester using the T-01 ball-on-disc method. The obtained data enabled the characterization of the wear process of the tested materials.

Testing for Abrasion Resistance of WC-Co Composites for Blades Used in Wood-Based Material Processing

Commonly used tool materials for machining wood-based materials are WC-Co carbides. Although they have been known for a long time, there is still much development in the field of sintered tool materials, especially WC-Co carbides and superhard materials. The use of new manufacturing methods (such as FAST-field-assisted sintering technology), which use pulses of electric current for heating, can improve the properties of the materials used for cutting tools, thereby increasing the cost-effectiveness of machining. The ability to increase tool life without the downtime associated with tool wear allows significant cost savings, particularly in mass production. This paper presents the results of a study of the effect of grain size and cobalt content of carbide tool sinters on the tribological properties of the materials studied. The powders used for consolidation were characterised by irregular shape and formed agglomerates of different sizes. Tribological tests were carried out using the T-01 (ball-on-disc) method. In order to determine the wear kinetics, the entire friction path was divided into 15 cycles of 200 m and the weight loss was measured after each stage. In order to determine the mechanism and intensity of wear of the tested materials under technically dry friction conditions, the surface of the tested sinters was observed before the test and after 5, 10, and 15 cycles. The conclusions of the study indicate that the predominant effect of surface cooperation at the friction node is abrasion due to the material chipping that occurs during the process. The results confirm the influence of sintered grain size and cobalt content on durability. In the context of the application of the materials in question for cutting tools, it can be pointed out that sintered WC(0.4)_4 has the highest potential for use in the manufacture of cutting tools.