Synthesis and thermal expansion of ZrO2/ZrW2O8 composites

Abstract

In this work, a ceramic composite of ZrW 2 O 8 and ZrO 2 was synthesized, in order to investigate the possibility of compensating the positive thermal expansion of ZrO 2 with the negative thermal expansion (NTE) compound ZrW 2 O 8 , tailoring the thermal expansion of these composites. The NTE material was mixed with varying amounts of ZrO 2 . The thermal expansion coefficients of this series of composites decrease with increasing amounts of ZrW 2 O 8 . Nevertheless, a negative deviation from the values expected by the rule of mixtures was found to be most pronounced in the middle of the compositional region.

Synthesis of ZrO2/ZrW2O8 composites with low thermal expansion

“…ZrO 2 has been widely used in optical, electrical fields. The synthesis and thermal expansion of ZrO 2 /ZrW 2 O 8 composites have been reported recently [15,16]. In this study, ZrO 2 /ZrW 2 O 8 composites were synthesized and the thermal expansion properties were studied.…”

Synthesis and thermal expansion of 4J36/ZrW2O8 composites

“…Compared with a standard XRD pattern, a little WO3 was found in the -ZrW 2 O 8 powder samples. ZrW 2 O 8 powder was pressed into a 25 mm × 4 mm × 4 mm sample, sintered at 1130C for 1 h and then air cooled.…”

“…However, when refined by low melting temperature of ZrW 2 O 8 (1220-1250C), the density and strength of the composite are low because the sintering temperature of the composite (1200C) is far below the ordinary sintering temperature of ZrO 2 (usually 1700C). When adding less than 0.25 wt.% Al 2 O 3 as assistant reagent, the density of the composite effectively increases, and the influence on the thermal expansion property of the composite is slight as well [3][4]. The ZrW 2 O 8 /Al6013 composite, prepared through-moulding pressure infiltration, contains 63 vol.% ZrW 2 O 8 and has a thermal expansion coefficient of 3.3  10 6 /C from ambient temperature to 400C [5].…”

Maximizing negative thermal expansion via rigid unit modes: a geometry-based approach

“…This argument is made stronger by the fact that, in the case of the Type II rectangles or Type β rhombi, the maximum area coverage of All this is very significant as major efforts are underway in order to design and produce materials with specific thermal expansion properties, as it is well known that a CTE mismatch of the system which is in thermal contact, could result in undesirable, and usually very costly, repercussions. In fact, one of the main uses of NTE materials is to combine them with existing conventional ones so as to adjust the overall thermal expansion coefficient of the resultant material [56]. In this respect, invar-type materials and other near-zero thermal expansion composite materials (normally composed of negatively and positively expanding materials in the correct ratio), which effectively result in a net expansion coefficient of zero, are of a high practical value [57,58].…”