The effects of H3PO4 and Ca（H2PO4）2 on compressive strength, water resistance, hydration process of thermally decomposed magnesium oxychloride cement （TDMOC） pastes were studied. The mineral composition, hydration...The effects of H3PO4 and Ca（H2PO4）2 on compressive strength, water resistance, hydration process of thermally decomposed magnesium oxychloride cement （TDMOC） pastes were studied. The mineral composition, hydration products and hydration heat release were analyzed by XRD, FT-IR, SEM and TAM air isothermal calorimeter, etc. After being modified by H3PO4 and Ca（HzPO4）2, the properties of the TDMOC are improved obviously. The compressive strength increases from 14.8 MPa to 48.1 MPa and 37.1 MPa, respectively. The strength retention coefficient （Kn） increases from 0.38 to 0.99 and 0.94, respectively. The 24 h hydration heat release decreases by 10% and 4% and the time of hydration peak appearing is delayed from 1 h to about 10 h. The XRD, FT-IR and SEM results show that the main composition is 5Mg（OH）z＇MgCIz＇8H20 in the modified TDMOC pastes. The possible mechanism for the strength enhancement was discussed. The purposes are to extend the potential applications of the salt lake magnesium resources and to improve the mechanical properties of TDMOC.展开更多
A method was established for the analysis of omethoate and it’s concomitants and decomposed product in biological samples by GC-MS.This method is rapid,reliable and accurate.
Thermal decomposition of[R<sub>4</sub>N][FeCo<sub>3</sub>（CO）<sub>12</sub>][I]（R=ethyl,butyl,hexadecyl,benzyltrimethyl,benzyltriethyl）in n-heptane,toluene and methanol was inves...Thermal decomposition of[R<sub>4</sub>N][FeCo<sub>3</sub>（CO）<sub>12</sub>][I]（R=ethyl,butyl,hexadecyl,benzyltrimethyl,benzyltriethyl）in n-heptane,toluene and methanol was investigated bythe in situ high pressure IR spectroscopic method.The results show that underhydroformylation conditions all clusters decompose to Co<sub>2</sub>（CO）<sub>8</sub>,Fe（CO）<sub>5</sub> and the salt ofCo（CO）<sub>4</sub><sup>-</sup>,and Co<sub>2</sub>（CO）<sub>8</sub> reacts with H<sub>2</sub> to form HCo（CO）<sub>4</sub>.Thermal stability of theclusters decrease with the increase of polarity of solvents.Under the hydroformylation con-ditions,IR spectra of the clusters are compatible with those of Fe（CO）<sub>5</sub>+Co<sub>2</sub>（CO）<sub>8</sub>+[R<sub>4</sub>N]Cl system.Because of the stabilizing effect or tetra-alkylammonium cation,when the tem-perature drops below 50℃ after decomposition of the clusters,the characteristic absorptionbands of the clusters appear again,so the decomposition process is reversible.展开更多
基金Project(B0210)supported by One Hundred Talent Project of Chinese Academy of SciencesProject(2008-G-158)supported by Science and Technology Tackling Key Program of Qinghai Province,China
文摘The effects of H3PO4 and Ca（H2PO4）2 on compressive strength, water resistance, hydration process of thermally decomposed magnesium oxychloride cement （TDMOC） pastes were studied. The mineral composition, hydration products and hydration heat release were analyzed by XRD, FT-IR, SEM and TAM air isothermal calorimeter, etc. After being modified by H3PO4 and Ca（HzPO4）2, the properties of the TDMOC are improved obviously. The compressive strength increases from 14.8 MPa to 48.1 MPa and 37.1 MPa, respectively. The strength retention coefficient （Kn） increases from 0.38 to 0.99 and 0.94, respectively. The 24 h hydration heat release decreases by 10% and 4% and the time of hydration peak appearing is delayed from 1 h to about 10 h. The XRD, FT-IR and SEM results show that the main composition is 5Mg（OH）z＇MgCIz＇8H20 in the modified TDMOC pastes. The possible mechanism for the strength enhancement was discussed. The purposes are to extend the potential applications of the salt lake magnesium resources and to improve the mechanical properties of TDMOC.
文摘A method was established for the analysis of omethoate and it’s concomitants and decomposed product in biological samples by GC-MS.This method is rapid,reliable and accurate.
基金This work was supported by the Science Foundation of Chinese Academy of Sciences.
文摘Thermal decomposition of[R<sub>4</sub>N][FeCo<sub>3</sub>（CO）<sub>12</sub>][I]（R=ethyl,butyl,hexadecyl,benzyltrimethyl,benzyltriethyl）in n-heptane,toluene and methanol was investigated bythe in situ high pressure IR spectroscopic method.The results show that underhydroformylation conditions all clusters decompose to Co<sub>2</sub>（CO）<sub>8</sub>,Fe（CO）<sub>5</sub> and the salt ofCo（CO）<sub>4</sub><sup>-</sup>,and Co<sub>2</sub>（CO）<sub>8</sub> reacts with H<sub>2</sub> to form HCo（CO）<sub>4</sub>.Thermal stability of theclusters decrease with the increase of polarity of solvents.Under the hydroformylation con-ditions,IR spectra of the clusters are compatible with those of Fe（CO）<sub>5</sub>+Co<sub>2</sub>（CO）<sub>8</sub>+[R<sub>4</sub>N]Cl system.Because of the stabilizing effect or tetra-alkylammonium cation,when the tem-perature drops below 50℃ after decomposition of the clusters,the characteristic absorptionbands of the clusters appear again,so the decomposition process is reversible.
