Abstract
In this paper, Al2O3–ZrO2 composites with an addition of 20 wt% TiN and 10 wt% TiC were modified. The addition of zirconia in a range from 2 to 5 wt% of the monoclinic phase and 10 wt% of Y2O3 stabilised ZrO2 affected the mechanical properties of the composites. A new type of sintering technique—the spark plasma sintering (SPS) method—within a temperature range from 1575 °C to 1675 °C, was used. Vickers hardness, apparent density, wear resistance and indentation fracture toughness KIC(HV) were evaluated at room temperature. An increase of the sintering temperature resulted in an improvement of Vickers hardness and an increase of the fracture toughness of the tested composites. The tribological properties of the samples were tested using the ball-on-disc method. The friction coefficient was in a range from 0.31 to 0.55, depending on the sintering temperature. An enhancement of the specific wear rate was dependent on the sintering temperature. The mechanical properties of the samples sintered by pressureless sintering (PS) were compared. X-ray diffraction patterns were presented in order to determine the phase composition. SEM microstructure of the tested composites sintered at different temperatures was observed.
Highlights
The technical performance capabilities of traditional tool materials are no longer sufficient to solve many machining problems, so these materials are successively replaced by new ones, including by sintered ceramic materials made with the use of new technologies
After pressureless sintering of the TCN1* specimen at the highest temperature of 1750 ◦ C, the following mechanical and physical properties were obtained: Vickers hardness HV1 of 17.4 GPa, critical stress intensity factor KIC(HV) of 4.46 MPa·m1/2, Young modulus of 378 GPa, apparent density of 4.21 g/cm3, and relative density of 97.03%. Such a high sintering temperature was used for this specimen, its mechanical properties were 10–25% lower compared to specimens sintered at the highest temperature (1675 ◦ C) and even 5–10% lower compared to those sintered at the lowest temperature (1575 ◦ C)
Effort has been made to produce alumina–zirconia matrix composites reinforced with Titanium carbide (TiC) and Titanium nitride (TiN) phases as a tool material with improved mechanical properties
Summary
The technical performance capabilities of traditional tool materials are no longer sufficient to solve many machining problems, so these materials are successively replaced by new ones, including by sintered ceramic materials made with the use of new technologies. Due to the disappearing resources of heavy and high-melting metals and the associated high costs, the growing interest in ceramic matrix composites is due to economic reasons. Alumina is the most important, widely used and cost-effective oxide ceramic material with perfect properties, such as high thermal resistance, good chemical stability, low density, high hardness and wear resistance, but has relatively low reliability. This is shown by the low fracture toughness KIC and the large dispersion of mechanical properties, reflected by the low values of the Weibull module m [2]. Ceramic composites in which the alumina matrix is reinforced with
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