Densely sintered carbide-silicon ceramics on a glass-crystal binder of cordierite composition

Abstract

The high density of silicon carbide ceramics is a prerequisite for obtaining materials with high strength. A promising technology for preparation of such materials at relatively low temperatures is the use of glass crystal bonds. The paper presents the results of studies on ceramic materials based on silicon carbide using glass in the pseudoternary system MgO–Al2O3–SiO2 as a glass binder. The composition of the glass corresponds to a ternary eutectic with a temperature of 13650C, which is located at the boundary of the primary crystallization fields, where one of the phases is cordierite. It has been determined that it is necessary to mechanically activate the components of the raw material mixture to obtain densely sintered ceramics. In this case, the most rational ratio between SiC filler and glass binder, which provides the maximum mechanical compressive strength (up to 700 MPa), is 60:40. It has been established that the crystallization of the glass binder plays a decisive role in determining the formation temperature of dense silicon carbide materials. The compaction occurs due to the movement of dispersed silicon carbide particles in the softened glass melt under the influence of thermal vibrations. The subsequent process of fine-dispersed crystallization of the glass binder during cooling during firing provides strengthening of the structure of the synthesized materials. The proposed integrated approach to the intensification of the sintering process is promising for obtaining durable silicon carbide ceramics with low synthesis temperatures (up to 16000C). A sufficiently high strength of the experimental ceramics will ensure its competitiveness with respect to traditional materials, including those used as wear and impact resistant.