Joining Of ZrO₂ Ceramics By Microwave Heating

Joining technology of ceramics, have been paid extensive attention on study andapplications. It provided a probability to fabricate larger or complex components frombasic shaped ceramic bodies with low cost and simple operation. Its significance maymatch with that of welding technologyto metal material.In this work, ceramics joining of sintered bodies containing medium layers wereconcerned. Based on the characteristics of that SiC absorbed microwave energy fromroom temperature but oxide from 600℃, and that SiC would be oxidated to SiO2 withvolume expanding at elevated temperature, interlayer composites containing SiCcomponent were designed. The ZrO₂ sintered ceramics were successfully joinedtogether by selective microwave heating at interlayer with far higher temperature thanjoined matrix.The joining mechanism was analyzed, and refered to thermodynamicscomputation of interfacial reaction, as well based on experiments, the best microwavesintering power was determinated as 3kW. It was showed that a microwave powerincrease rate as 1kW/20min could result in the best joining effect. From the result, theinterlayer which contained 40wt% ZrO₂ and 60wt% SiC achieved the best joiningeffect. It was supposed that a suitable expanding by SiC oxiding might take placeunder that component condition, also that forming of SiO2, a main phase resulted byreaction of O2 and SiC, might promote the interfacial contacts by mass transfer duo toits sticky flow at elevating temperature. Based on a series of tests concerninginterlayer thickness and joining pressure, it was illustrated that the best joining effectwas achieved under conditions that covered by ZrO₂ power, tiny pressure and thinnerthickness,namelythe interlayer contains 25wt% solid content.