Improving the Tribological Properties of Ceramic Dies

The article is devoted to tribological studies of a ceramic composite with a zirconia-based die in order to replace carbide wire drawing dies with ceramic. Sliding friction was done according to the scheme finger-disk without lubrication and with lubrication. The wear rate and friction coefficients were determined, on the basis of which it is proposed to produce portage dies-blanks from zirconium ceramics. The influence of sintering temperature on the mechanical properties of ceramics, especially cracking resistance, was studied. The optimum sintering temperature was determined by the criterion of fracture toughness. The formation of defects after the final firing was investigated. It was found that sintering at a temperature of 1600 ° C is more promising. An trial batch of zirconium ceramic dies showed positive results in the process of drawing copper wire in industrial situations.

Semi-Sintered Medical Zirconia Ceramic Used for Denture CAM Processing

CAD/CAM technology has been widely applied in the field of oral restoration, which creates a revolutionary change in the pattern of traditional handmade denture and puts forward new demands on the past medical dental restorative material. The materials used for making dentures should own good machining properties and biocompatibilities. Medical zirconium ceramic have a broad prospect in the field of oral restoration because of its features are high strength, high toughness, good biocompatibility, high similarity of performance and aesthetic effect of processed dentures to real dentals. Dental restoration was obtained initially by NC machining using the feature that zirconium ceramic was not fully hardened but had a definite range of strength in the semi-sintered state. Experimental results shown that the ceramic denture machined by this processing has better surface quality and can satisfy requirements of oral restoration. Observation results shown that cutting surfaces were smooth, grinding cracks were tiny and uniform, and there were no obvious fracture gaps on edges and complex irregular surface of neck could be better reflected.

Physical-Mechanical Properties of Corundum-Zirconium Ceramic Obtained by the Technology of Radial Magnetoimpulse Pressing

The paper presents comparative studies of physical-mechanical properties of long-measured/elongated corundum-zirconium ceramic with different phase ration, manufactured with the use of the radial magnetoimpulse press. The optimal mode of pressing of ultra-dispersed powders was developed, where the amplitude of magnetoimpulse pressure is 1.14 GPа at acceleration time-120 mcs. We obtained the corundum-zirconium ceramic with the grain size 0.35-0.5 μm and the coherent-scattering regions of 0.050-0.120 μm, possessing microhardness 10.6-12.9 GPа and crack-resistance 5.5-7.8 MPа·m1/2.

Influence of Phase Composition on Properties of Corundum-Zirconium Ceramic

The results of the analysis of influence of the phase composition of corundum-zirconium ceramic on its properties are presented in this paper. It was established that the most perspective ceramic has composition 0,6 (ZrО2 + 3M% Y2O3) – 0,4 Аl2О3. High strength properties of this composition are determined by the presence of compressive stresses and the opportunity of retaining of tetragonal grains ZrО2 in a metastable condition at low temperatures.