Study On The Design And Properties Of Corundum/mullite Laminated Composites

Corundum-mullite composites?CMC?have good chemical stability,high temperature strength and excellent thermal shock resistance,which is often used in furnace lining,kiln furniture and other refractory materials.However,domestic alumina-mullite kiln furniture products still exist some problems,such as poor thermal shock stability and low service life.Since the layered laminate can effectively improve the fracture toughness of ceramic materials through the synergy effect among layers,corundum-mullite layered composites,using high-purity corundum,mullite,activated alumina micropowder and silicon micropowder as raw materials,were prepared by macroscopic structural lamination and interface characteristics control combining with finite element simulation analysis.In particular,the relationship between macroscopic structural lamination and thermal shock resistance was investigated.The main results are as follows:?1?Preparation and properties of single layer CMC.The sintering temperatures?1350?,1450?,1550?and 1650??,matrix contents?30%,40%,50%and 60%?and additives?AlF₃·3H₂O and Al?OH?₃?have great influences on the properties of the CMC.The cold modulus of rapture?CMOR?and residual cold modulus of rapture ratio?residual CMOR ratio?of the CMC sample with 40%matrix sintered at 1550°C for 3h was 7.58 MPa and 89.08%,respectively.Moreover,the in-situ formation of acicular mullite whiskers could be sinificantly promoted by the introduction of 3wt.%AlF₃·3H₂Oand 5wt.%Al?OH?₃ additives,which is beneficial to reduce stress concentration and prevent or delay the propagation of microcracks,the strength and thermal shock resistance of CMC were consequently improved and the corresponding CMOR and residual CMOR ratio values were increased to 14.66 MPa and 83.5%,respectively.?2?The effects of different interface additives?AlF₃·3H₂O,V₂O₅,TiO₂ and ZrO₂?on the properties of corundum/mullite laminated composites?CMLC?prepared by cold press lamination technique were investigated.The CMOR and residual CMOR ratio of seven-layer and equal-thick CMLC?with 30%matrix in outer layer and 40%matrix in inner layer?calcined at 1550°C for 3 h were 6.45 MPa and 95.52%respectively.In comparison with AlF₃·3H₂O,TiO₂ and ZrO₂ interface additives,the addition of V₂O₅interface additive was more useful to improve the strength and thermal shock resistance of the seven-layer CMLC,and the CMOR and residual CMOR ratio of the CMLC with V₂O₅ interface additive was increased to 10.10 MPa and 95.57%,respectively.?3?Preparation and properties of lightweight CMLC.The CMC sample A5?containing 5%alumina hollow spheres?calcined at 1550°C for 3 h has better thermal shock resistance,and the CMOR and residual CMOR ratio of the sample?A5?are 8.13MPa and 98.4%,respectively.The temperature-stress field of CMC sample?A5 and A60?and three-layer CMLC sample?A60@A5@A60?were analyzed by ANSYS finite element simulation,it was found that the sample A60@A5@A60 with an inner thickness of 17 mm has the maximum stress in the Z-axis direction.Correspondingly,the CMLC sample A60@A5@A60 with an inner layer thickness of 14 mm has lower strength,higher elastic modulus,and better thermal shock resistance after calcining at1550°C for 3 h.