The SiC whiskers (SiCw) synthesized from rice hulls is studied in this paper. The properties of the application in the composite materials are tested, and also compared with the SiCw produced in US and Japan, the resu...The SiC whiskers (SiCw) synthesized from rice hulls is studied in this paper. The properties of the application in the composite materials are tested, and also compared with the SiCw produced in US and Japan, the results indicate that the SiCw produced by this method is mainly straight crystals with multi nodes on face, the main type is P-SiC. lt has many advantages such as high strength and excellent oxidation resistance to high temperature. The Si3N4 ceramic composite materials reinforced and toughened with the SiCw, δfRT of the material is (856±22)MPa, δf300℃ is approximately (418. 5±14. 2) MPa and Klc is approximately (11. 3±1. 0) MPa m1/2. Besides, the application of the SiCw in the engineering materials of mining is forecasted.展开更多
The waste-to-energy(WTE)technologies are now recovering energy and materials from over 300 million tonnes of municipal solid wastes worldwide.Extensive studies have investigated substituting natural construction mater...The waste-to-energy(WTE)technologies are now recovering energy and materials from over 300 million tonnes of municipal solid wastes worldwide.Extensive studies have investigated substituting natural construction materials with WTE residues to relieve the environmental cost of natural resource depletion.This study examined the beneficial uses of WTE residues in civil engineering applications and the corresponding environmental standards in Europe,the U.S.,and China.This review presents the opportunities and challenges for current technical approaches and the environmental standards to be met to stabilize WTE residues.The principal characteristics of WTE residues(bottom ash and fly ash)and the possible solutions for their beneficial use in developed and developing countries are summarized.The leaching procedures and environmental standards for pH,heavy metals,and polychlorinated dibenzo-p-dioxins/furans(PCDD/Fs)are compared.The current practice and engineering properties of materials using WTE residues,including mixtures with stone aggregate or sand,cement-based or hot-mix asphalt concrete(pavement),fill material in the embankments,substitute of Portland cement or clinker production,and ceramic-based materials(bricks and lightweight aggregate)are comprehensively reviewed.展开更多
文摘The SiC whiskers (SiCw) synthesized from rice hulls is studied in this paper. The properties of the application in the composite materials are tested, and also compared with the SiCw produced in US and Japan, the results indicate that the SiCw produced by this method is mainly straight crystals with multi nodes on face, the main type is P-SiC. lt has many advantages such as high strength and excellent oxidation resistance to high temperature. The Si3N4 ceramic composite materials reinforced and toughened with the SiCw, δfRT of the material is (856±22)MPa, δf300℃ is approximately (418. 5±14. 2) MPa and Klc is approximately (11. 3±1. 0) MPa m1/2. Besides, the application of the SiCw in the engineering materials of mining is forecasted.
文摘The waste-to-energy(WTE)technologies are now recovering energy and materials from over 300 million tonnes of municipal solid wastes worldwide.Extensive studies have investigated substituting natural construction materials with WTE residues to relieve the environmental cost of natural resource depletion.This study examined the beneficial uses of WTE residues in civil engineering applications and the corresponding environmental standards in Europe,the U.S.,and China.This review presents the opportunities and challenges for current technical approaches and the environmental standards to be met to stabilize WTE residues.The principal characteristics of WTE residues(bottom ash and fly ash)and the possible solutions for their beneficial use in developed and developing countries are summarized.The leaching procedures and environmental standards for pH,heavy metals,and polychlorinated dibenzo-p-dioxins/furans(PCDD/Fs)are compared.The current practice and engineering properties of materials using WTE residues,including mixtures with stone aggregate or sand,cement-based or hot-mix asphalt concrete(pavement),fill material in the embankments,substitute of Portland cement or clinker production,and ceramic-based materials(bricks and lightweight aggregate)are comprehensively reviewed.
