Investigation On Properties Of Magnesia Carbon Refractories Bonded With Environmentally Friendly Complex Magnesia Alumina Cementing Agent

To investigate the application prospect of environmentally friendly complex magnesia alumina cementing agents in magnesia carbon refractories,an environmentally friendly complex magnesia alumina cementing agent was adopted as the binder in this work.Through the component analysis,phase analysis,infrared spectroscopy analysis,comprehensive thermal analysis,microstructure analysis,and conventional properties testing,the performance and bonding mechanism of the cementing agent were explored.The effects of the cementing agent addition,carbon source,graphite addition,temperature,etc.on the properties of magnesia carbon refractories were studied.And their properties were compared with those of phenolic resin bonded magnesia carbon refractories.After mixing the complex magnesia alumina cementing agent with water,the combined action of the hydration reaction of active magnesia,the complexation reaction of glucose and citric acid with magnesia,and the dehydration condensation reaction of glucose and citric acid with other organics produce bonding strength.At 600～1100,the decomposition and carbonization of organics decrease the bonding strength of the materials.At1100～1500,the in-situ spinelization of the complex magnesia alumina cementing agent and the sintering between the particles inside the materials gradually increase the strength of the materials.With the drying system of 110 for 24 h,extra adding 3.5wt% complex magnesia alumina cementing agent is appropriate.Compared with Carbores P,magnesia carbon refractories with graphite as the carbon source show slightly poorer physical properties,lower hot strength,worse slag penetration resistance,and better antioxidation.With the graphite addition increases from 2wt% to14wt%,the linear change rate of the materials gradually increases,the physical properties decrease,the hot strength ranges from 1.6 to 2.4MPa,and the slag penetration resistance gradually increases.Compared with phenolic resin bonded magnesia carbon refractories,complex magnesia alumina cementing agent bonded materials perform slightly worse physical properties and lower hot strength.Added with 2wt% graphite,the material has the cold compressive strength of 57.3MPa after drying and 50.3MPa after treatment at 1500,and the cold modulus of rupture after one thermal shock increases by 23.9%.Low carbon complex magnesia alumina cementing agent bonded magnesia carbon refractories have good mechanical properties and thermal shock resistance.Compared with phenolic resin,the complex magnesia alumina cementing agent is non-toxic and has no irritating odor,whose mixing process is more convenient,laying time is shorter,and drying temperature is lower,showing a good application prospect.