原料配比对硫氧镁水泥力学性能、物相和微观形貌的影响

Effect of Raw Material Ratio on Mechanical Properties, Phase and Micromorphology of Magnesium Oxysulfate Cement

以盐湖提锂副产镁渣为原料,经洗涤煅烧制备活性MgO,并与七水硫酸镁混合制备硫氧镁水泥。研究了原料配比(活性MgO:MgSO_(4):H_(2)O,摩尔比)对硫氧镁水泥试件凝结时间、安定性和抗压强度的影响,并利用XRD和SEM分析试件的物相组成和微观形貌。结果表明:固定H值,随着M值的增大,MOS浆体的凝结时间缩短,28 d的抗压强度先增加后降低,主要水化产物517相先增多后减少,晶体的微观形貌经历了由针丝状晶体—针丝状、短棒状晶体并存—凝胶状、针棒状晶体并存的转变过程;当M=9时,MOS浆体的安定性较差,主要水化产物逐渐变为Mg(OH)_(2)相;固定M值,随着H值的增大,MOS浆体的凝结时间延长,28 d的抗压强度先增加后降低,主要水化产物的种类没有发生明显的变化,当H≥26时,MOS浆体的安定性较差;得出较佳的M值范围为5~7,H值范围为20~24。

With the salt lake lithium by-product magnesium slag as raw material,the active MgO was prepared by washing calcination,and the magnesium oxysulfate cement was mixed with magnesium sulfate in seven water.The effects of raw material ratio(active MgO:MgSO_(4):H_(2)O,mole ratio)on the setting time,stability and pressure resistance of the magnesium oxysulfate cement specimen were studied,and the phase composition and microscopic morphology of the test pieces were analyzed by XRD and SEM.The results show that:fixed H value,with the increase of M value,MOS slurry condensation time is reduced,28 d pressure strength increases first and then decreases later,the main hydration product 517 phase increases first and decreases later,the microscopic appearance of the crystal has experienced by needle-wire crystal-needle-like short rod crystal co-existence-gel-like,needle-bar crystals coexist of the transformation process,when M=9,MOS slurry has poor stability,the main hydration product gradually become Mg(OH)_(2) phase;fixed M value,with the increase of H value,the condensation time of MOS slurry is extended,the pressure strength of 28 d is increased first and then decreased later,the main hydration product type does not change significantly,when H≥26,MOS slurry has poor stability is;It concluded that the better M value range is 5 to 7 and the H value range is 20 to 24.