The structure of Mo-15.16 Si, Mo-30 Si and Mo-36.3 Si (wt pct) elemental powder mixture during mechanical alloying was studied using electron microscopy and X-ray diffraction. It had been found that, in all the system...The structure of Mo-15.16 Si, Mo-30 Si and Mo-36.3 Si (wt pct) elemental powder mixture during mechanical alloying was studied using electron microscopy and X-ray diffraction. It had been found that, in all the systems under study, silicon disappeared initially during mechanical alloying (MA). In the Mo-Si systems all products were in form of amorphous state after long time milling, but there were different intermediate products. MoSi2 and Mo5Si3 intermetallic compounds in the Mo-30Si and Mo-36.3Si (wt pct) were directly synthesized from elements through inter-diffussion process. The high density of defects and interface of nano-crystal lines induced by ball milling would promote the reaction process. Only in the Mo-15.16Si (wt pct) system was Mo(Si) supersaturated solid solution formed as an intermediate product. Schematic free-energy diagram of Mo-Si system based on the thermodynamics was used to analyze the difference among the intermediate state products.展开更多
The direct determination of NO2 gas using a galvanic coulometric cell as detector by gas flow injection analysis (FIA) is described. The simple modification of the flow injection allows the linear range for the determ...The direct determination of NO2 gas using a galvanic coulometric cell as detector by gas flow injection analysis (FIA) is described. The simple modification of the flow injection allows the linear range for the determination of NO2 gas from 0. 01 - 2 ppm(v/v)to be expanded to 8- 500 ppm (v/v) with a relative standard deviation of 3 - 4% (n=12) at a rate of 25 samples per hour and avoids the problem of bine consuming in the equilibrium performance.展开更多
The flow rate sensitivity of membrane-covered oxygen gas sensor has been tested experimentally. the oxygen sensor,gas flowmeter,and air pump are arranged in six types of connective modes, the flow sensitivity of oxyge...The flow rate sensitivity of membrane-covered oxygen gas sensor has been tested experimentally. the oxygen sensor,gas flowmeter,and air pump are arranged in six types of connective modes, the flow sensitivity of oxygen sensor is notably different. Preliminary results on the positional flow rate sensitivity of oxygen gas sensor are reported.展开更多
文摘The structure of Mo-15.16 Si, Mo-30 Si and Mo-36.3 Si (wt pct) elemental powder mixture during mechanical alloying was studied using electron microscopy and X-ray diffraction. It had been found that, in all the systems under study, silicon disappeared initially during mechanical alloying (MA). In the Mo-Si systems all products were in form of amorphous state after long time milling, but there were different intermediate products. MoSi2 and Mo5Si3 intermetallic compounds in the Mo-30Si and Mo-36.3Si (wt pct) were directly synthesized from elements through inter-diffussion process. The high density of defects and interface of nano-crystal lines induced by ball milling would promote the reaction process. Only in the Mo-15.16Si (wt pct) system was Mo(Si) supersaturated solid solution formed as an intermediate product. Schematic free-energy diagram of Mo-Si system based on the thermodynamics was used to analyze the difference among the intermediate state products.
文摘The direct determination of NO2 gas using a galvanic coulometric cell as detector by gas flow injection analysis (FIA) is described. The simple modification of the flow injection allows the linear range for the determination of NO2 gas from 0. 01 - 2 ppm(v/v)to be expanded to 8- 500 ppm (v/v) with a relative standard deviation of 3 - 4% (n=12) at a rate of 25 samples per hour and avoids the problem of bine consuming in the equilibrium performance.
文摘The flow rate sensitivity of membrane-covered oxygen gas sensor has been tested experimentally. the oxygen sensor,gas flowmeter,and air pump are arranged in six types of connective modes, the flow sensitivity of oxygen sensor is notably different. Preliminary results on the positional flow rate sensitivity of oxygen gas sensor are reported.
