A novel carbon nanocomposite cement-based material for geothermal drilling and production(CNTs-CC)was developed to solve the problem of insufficient performance of existing thermal cementing cement.Firstly,with graphite and silicon nitride as main thermal conductivity filler,silicon powder as heat stabilization material and carbon nanotubes as co-reinforcing filler,the nano composite cement material base liquid was preliminarily developed.Secondly,based on the Box-Behnken experiment design of response surface method,17-sets of ratio optimization experiments were carried out,and a quadratic polynomial prediction model with 28 d compressive strength and thermal conductivity as the response indexes was constructed.The influences of various factors on the response indexes were investigated by combining analysis of variance and response surface,and the optimal ratio of cementable materials was obtained.Finally,the engineering properties of the cement-based composite materials were evaluated,and the hydration mechanism of the cement-based composite materials was studied by XRD and SEM.The results show that the thermal conductivity and compressive strength of cement-based composite materials are influenced by the interaction of many factors,in which the interaction between early strength agent and water reducing agent is significant.The 28 d compressive strength of CNTs-CC cement stone is 8.15 MPa,and the thermal conductivity is 2.236 W/(m·K).The thermal conductive filler does not participate in the hydration process,and the carbon nanotube powder can play a"filling"and"bridging"effect,and the admixture regulates the hydration process.
关键词
地热钻采/水泥基材料/石墨/氮化硅/碳纳米管/响应曲面/水化
Key words
geothermal drilling and production/cement-based material/graphite/silicon nitride/carbon nanotube/response surface/hydration
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