Microstructure and flexural strength of anorthite-diopside mixed phase

Low Temperature Co-fired Ceramics (LTCC) are widely used in electronic devices due to their ease of layering and outstanding applicability to RF technologies. These LTCC parts are manufactured by thick film process. However, unlike electronic devices of the past, modern portable electronic devices now require high strength materials, and LTCCs, which have a mixed glass and crystal phase, are relatively low strength materials. Thus their strength has been enhanced with crystallized glass induced by low temperature sintering. The most commonly used crystal phase is anorthite, but there is a comparative lack of research on other crystal phases or mixed phases and their strengths. Thus this study observed and compared the physical properties of mixed phases of synthesized anorthite and diopside at varying proportions. The two crystal phases were synthesized at the respective temperatures of 1300 °C and 1250 °C and as there was almost no change in the phases caused by the sintering process, mixed phases of varying proportions could be produced. The flexural strength of the sintered mixed phases increased along with the amount of anorthite but decreased for 100% anorthite. The decrease in flexural strength was judged to be caused by the presence of glass phase. This was tested by comparing the flexural strength and microstructure of sintered anorthite having varying Al<inf>2</inf>O<inf>3</inf> content. This enabled us to confirm indirectly that the glassy phase was the cause of decreased flexural strength.