發(fā)布時(shí)間：2019-07-06 06:12

【摘要】：磷酸鎂水泥(MPC)作為一種化學(xué)結(jié)合磷酸鹽膠凝材料,在常溫下即可發(fā)生化學(xué)反應(yīng),凝結(jié)硬化。它既具有陶瓷材料的質(zhì)硬、高強(qiáng)、耐高溫的特性又具有水泥材料的可塑性好、適應(yīng)性強(qiáng)、耐久性好的特性。由于其具有早強(qiáng)快硬、流動(dòng)性好、與舊混凝土之間適應(yīng)性好、粘結(jié)強(qiáng)度高、收縮小和免燒等諸多優(yōu)點(diǎn),在快速修補(bǔ)領(lǐng)域、核廢料處理領(lǐng)域已得到廣泛應(yīng)用,在屏蔽大型受輻射的核設(shè)施方面也具有潛在應(yīng)用。而核能作為一種高效、清潔的新型能源,在發(fā)電、醫(yī)療和食品殺菌等領(lǐng)域得到了廣泛應(yīng)用。但核能的利用也存在一定風(fēng)險(xiǎn),尤其因人為失誤或自然災(zāi)害導(dǎo)致的核泄漏而給人類和環(huán)境造成嚴(yán)重危害,在第一時(shí)間內(nèi)加強(qiáng)核材料和設(shè)施安全,防止放射性物質(zhì)泄漏以及輻射防護(hù)顯得尤其重要�；诖顺霭l(fā)點(diǎn),本論文針對γ射線快速屏蔽材料展開了系統(tǒng)研究,選擇具有快凝快硬特性的磷酸鎂水泥,與重晶石以及鉛粉復(fù)合,重點(diǎn)研究了重晶石摻量、鉛粉摻量對磷酸鎂快速屏蔽材料凝結(jié)時(shí)間、流動(dòng)度、抗壓強(qiáng)度、屏蔽性的影響;其次,借助XRD、SEM、水化熱、熱分析、孔結(jié)構(gòu)分析等分析手段研究對其物相組成、微觀結(jié)構(gòu)及熱力學(xué)性能影響。最后,對屏蔽性能較優(yōu)的重晶石-金屬鉛共摻快速屏蔽材料的環(huán)境適應(yīng)性、粘接強(qiáng)度、膨脹特性、浸出性及耐久性進(jìn)行了研究。通過磷酸鎂水泥快速屏蔽材料的研究,以期得到對γ射線具有良好屏蔽效能,同時(shí)具有較好的長期穩(wěn)定性的新型輻射防護(hù)材料。研究結(jié)果表明:重晶石部分替代重?zé)趸V可顯著降低磷酸鎂快速屏蔽材料的水化放熱,隨著重晶石摻量增加,磷酸鎂快速屏蔽材料的流動(dòng)度降低,凝結(jié)時(shí)間逐漸延長,抗壓強(qiáng)度先增加后降低。重晶石摻量為30%時(shí),抗壓強(qiáng)度最高,重晶石摻量達(dá)50%時(shí),其1d抗壓強(qiáng)度可達(dá)39.4MPa。加入鉛粉后,隨著鉛粉摻量增加,流動(dòng)度逐漸增大,抗壓強(qiáng)度總體呈現(xiàn)下降趨勢,鉛粉摻20%時(shí),其1d抗壓強(qiáng)度為27.0MPa。從屏蔽效果來看,單摻重晶石時(shí),隨著重晶石摻量的增加,磷酸鎂水泥快速屏蔽材料對γ射線的屏蔽率增大。重晶石摻量為50%時(shí),γ射線屏蔽率為57.7%。重晶石-金屬鉛共摻時(shí),隨著鉛粉摻量增加,磷酸鎂水泥快速屏蔽材料的γ射線屏蔽效果進(jìn)一步提高,鉛粉摻量為20%時(shí),γ射線屏蔽率可達(dá)70%。其它性能方面,磷酸鎂水泥快速屏蔽材料具有非常好的流動(dòng)性,環(huán)境適應(yīng)性強(qiáng),與舊混凝土之間粘接強(qiáng)度高,長期強(qiáng)度發(fā)展良好,鉛浸出小,化學(xué)穩(wěn)定性較好,抗凍融能力強(qiáng)。本論文制備的磷酸鎂水泥快速屏蔽材料的凝結(jié)時(shí)間≤30min,初始流動(dòng)度≥230mm,1d抗壓強(qiáng)度≥25MPa,1h粘接強(qiáng)度≥3MPa,既具有良好的輻射屏蔽性能,又可以作為快速修補(bǔ)材料,在核應(yīng)急快速處理方面具有良好的應(yīng)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 緯-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，

本文編號(hào)：2510844