磷酸镁水泥基快速屏蔽材料的制备及其性能研究

发布时间：2019-07-06 06:12

【摘要】：磷酸镁水泥(MPC)作为一种化学结合磷酸盐胶凝材料,在常温下即可发生化学反应,凝结硬化。它既具有陶瓷材料的质硬、高强、耐高温的特性又具有水泥材料的可塑性好、适应性强、耐久性好的特性。由于其具有早强快硬、流动性好、与旧混凝土之间适应性好、粘结强度高、收缩小和免烧等诸多优点,在快速修补领域、核废料处理领域已得到广泛应用,在屏蔽大型受辐射的核设施方面也具有潜在应用。而核能作为一种高效、清洁的新型能源,在发电、医疗和食品杀菌等领域得到了广泛应用。但核能的利用也存在一定风险,尤其因人为失误或自然灾害导致的核泄漏而给人类和环境造成严重危害,在第一时间内加强核材料和设施安全,防止放射性物质泄漏以及辐射防护显得尤其重要。基于此出发点,本论文针对γ射线快速屏蔽材料展开了系统研究,选择具有快凝快硬特性的磷酸镁水泥,与重晶石以及铅粉复合,重点研究了重晶石掺量、铅粉掺量对磷酸镁快速屏蔽材料凝结时间、流动度、抗压强度、屏蔽性的影响;其次,借助XRD、SEM、水化热、热分析、孔结构分析等分析手段研究对其物相组成、微观结构及热力学性能影响。最后,对屏蔽性能较优的重晶石-金属铅共掺快速屏蔽材料的环境适应性、粘接强度、膨胀特性、浸出性及耐久性进行了研究。通过磷酸镁水泥快速屏蔽材料的研究,以期得到对γ射线具有良好屏蔽效能,同时具有较好的长期稳定性的新型辐射防护材料。研究结果表明:重晶石部分替代重烧氧化镁可显著降低磷酸镁快速屏蔽材料的水化放热,随着重晶石掺量增加,磷酸镁快速屏蔽材料的流动度降低,凝结时间逐渐延长,抗压强度先增加后降低。重晶石掺量为30%时,抗压强度最高,重晶石掺量达50%时,其1d抗压强度可达39.4MPa。加入铅粉后,随着铅粉掺量增加,流动度逐渐增大,抗压强度总体呈现下降趋势,铅粉掺20%时,其1d抗压强度为27.0MPa。从屏蔽效果来看,单掺重晶石时,随着重晶石掺量的增加,磷酸镁水泥快速屏蔽材料对γ射线的屏蔽率增大。重晶石掺量为50%时,γ射线屏蔽率为57.7%。重晶石-金属铅共掺时,随着铅粉掺量增加,磷酸镁水泥快速屏蔽材料的γ射线屏蔽效果进一步提高,铅粉掺量为20%时,γ射线屏蔽率可达70%。其它性能方面,磷酸镁水泥快速屏蔽材料具有非常好的流动性,环境适应性强,与旧混凝土之间粘接强度高,长期强度发展良好,铅浸出小,化学稳定性较好,抗冻融能力强。本论文制备的磷酸镁水泥快速屏蔽材料的凝结时间≤30min,初始流动度≥230mm,1d抗压强度≥25MPa,1h粘接强度≥3MPa,既具有良好的辐射屏蔽性能,又可以作为快速修补材料,在核应急快速处理方面具有良好的应用前景。
[Abstract]:Magnesium phosphate cement (MPC), as a kind of chemical binding phosphate cementitious material, can react and harden at room temperature. It not only has the characteristics of hard, high strength and high temperature resistance of ceramic materials, but also has the characteristics of good plasticity, adaptability and durability of cement materials. Because of its advantages of early strength and fast hardening, good mobility, good adaptability with old concrete, high bond strength, shrinkage and no burning, it has been widely used in the field of rapid repair, and also has potential applications in shielding large-scale irradiated nuclear facilities. As a new type of energy with high efficiency and cleanliness, nuclear energy has been widely used in power generation, medical treatment and food sterilization. However, there are some risks in the use of nuclear energy, especially the nuclear leakage caused by human error or natural disaster, which causes serious harm to human beings and the environment. It is particularly important to strengthen the safety of nuclear materials and facilities in the first time, to prevent the leakage of radioactive materials and radiation protection. Based on this starting point, this paper carried out a systematic study on gamma-ray rapid shielding materials, selected magnesium phosphate cement with fast setting and fast hardening characteristics, combined with barite and lead powder, focusing on the effects of barite content and lead powder content on the setting time, mobility, compressive strength and shielding property of magnesium phosphate rapid shielding materials. Secondly, the effects of XRD,SEM, hydration heat, thermal analysis and pore structure analysis on its phase composition, microstructure and thermodynamic properties were studied. Finally, the environmental adaptability, adhesive strength, expansion characteristics, leaching and durability of barite-lead co-mixed rapid shielding materials with better shielding performance were studied. Through the study of magnesium phosphate cement rapid shielding material, a new type of radiation protection material with good shielding effectiveness and good long-term stability for gamma-ray shielding can be obtained. The results show that the hydration and heat release of magnesium phosphate rapid shielding material can be significantly reduced by partly replacing reburned magnesium oxide by barite. With the increase of barite content, the mobility of magnesium phosphate rapid shielding material decreases, the setting time prolongs gradually, and the compressive strength first increases and then decreases. When the content of barite is 30%, the compressive strength is the highest, and when the content of barite is 50%, the compressive strength of barite can reach 39.4 MPA. After adding lead powder, the mobility increases gradually with the increase of lead powder content, and the compressive strength decreases as a whole. When the lead powder is 20%, the 1-day compressive strength is 27.0 MPA. From the point of view of shielding effect, with the increase of barite content, the shielding rate of magnesium phosphate cement rapid shielding material to 纬-ray increases with the increase of barite content. When the content of barite is 50%, the shielding rate of gamma ray is 57.7%. When barite and lead are co-mixed, the gamma-ray shielding effect of magnesium phosphate cement rapid shielding material is further improved with the increase of lead powder content. When the lead powder content is 20%, the gamma-ray shielding rate can reach 70%. In other aspects, magnesium phosphate cement rapid shielding material has very good mobility, strong environmental adaptability, high bonding strength with old concrete, good long-term strength development, small lead leaching, good chemical stability and strong freeze-thaw resistance. The setting time of magnesium phosphate cement rapid shielding material prepared in this paper is 鈮，

本文编号：2510844