Abstract: In order to improve the hydration resistance of magnesia-calcia materials and further enhance other properties,magnesia-calcia clinker samples were prepared using dolomite powder and light-burned magnesia powder as the main raw materials,phenolic resin as the binder,extra adding nano TiO₂,molding at 100 MPa,and calcining at 1 650 ℃ for 3 h.Effect of TiO₂ additions (0,2%,4%,6%,and 8%,by mass) on the properties of the samples was investigated.The results show that the introduction of nano TiO₂ can generate solid solution in the materials and promote grains growth,while new phases CaTiO₃ and Ca₄Ti₃O₁₀ are generated to improve the bonding degree of particles;but the excessive generation of the new phases will hinder the gas discharge in the materials and affect the sintering process.With the increase of the nano TiO₂ addition,the content of CaTiO₃ and Ca₄Ti₃O₁₀ in the samples increases,the bulk density decreases gradually,the apparent porosity increases,and the cold modulus of rupture,the cold crushing strength and the hydration resistance,as well as the cold modulus of rupture after thermal shock firstly increase and then decrease.The strength,the thermal shock resistance and the hydration resistance of the samples are the highest when the nano TiO₂ addition is 2%.

Key words: magnesia-calcia materials, nano TiO₂, mechanical property, hydration resistance

摘要： 为了改善镁钙材料的抗水化性能并进一步提高其他性能,以白云石粉和轻烧镁粉为主要原料,外加纳米TiO₂,以酚醛树脂为结合剂,在100 MPa下成型,经1 650 ℃煅烧3 h制成镁钙砂试样,研究了TiO₂外加量(外加质量分数分别为0、2%、4%、6%和8%)对其性能的影响。结果表明:纳米TiO₂的引入可使材料内产生固溶体,促进晶粒长大,同时材料内会有新相CaTiO₃和Ca₄Ti₃O₁₀生成,提高颗粒间结合程度,但过量的新相生成会阻碍材料内气体排出,影响烧结过程。随着纳米TiO₂外加量的增加,试样中CaTiO₃和Ca₄Ti₃O₁₀的含量增加,体积密度逐渐降低,显气孔率逐渐增大,常温抗折强度、常温耐压强度和抗水化性能以及热震后的常温抗折强度先增大后减小。当纳米TiO₂外加量为2%(w)时,试样的强度、抗热震性和抗水化性能最高。

关键词: 镁钙材料, 纳米TiO₂, 力学性能, 抗水化性