BaMgAl_(10)O_(17)∶Eu(BAM)蓝粉热劣化机理研究

提出了BAM的热劣化模型 ,该模型能较好地说明热处理气氛中含氧量同BAM热劣化程度的关系。BAM的热劣化程度ΔZ与气氛中氧分压的 1/ 6次方 (PO2 )成正比 ,符合关系式ΔZ =α(PO2 ) 1/ 6+ β。α是与温度有关的参数 ,随温度升高 ,α增大 ;β在数值上等于氧分压为零时的ΔZ值。按照上述关系式 ,作者对热劣化实验数据作了拟合 。

Sr_2MgSi_2O_7∶Eu^(2+),Dy^(3+)长余辉发光材料的热劣化机理研究

Sr_2MgSi_2O_7∶Eu^(2+),Dy^(3+)存在热稳定性不好、热劣化机理不明确的问题,为了探讨其热劣化机理,在不同温度下对其进行热处理,表征了余辉性能和光谱性质,研究了热处理温度对余辉性能和发射强度的影响。结果表明,当热处理温度低于600℃时,余辉性能变化不明显,发射强度随热处理温度升高而缓慢降低;而高于600℃的热处理温度可以使余辉性能显著劣化,且随热处理温度的升高,发射强度呈现先增大后减小趋势,并在900℃附近出现极大值。上述余辉性能劣化和发射强度变化的根本原因是陷阱能级捕获电子能力的减弱,在此基础上提出了Sr_2MgSi_2O_7∶Eu^(2+),Dy^(3+)热劣化的陷阱能级受热破坏机理。

Deterioration mechanism and rapid detection of performances of an existing subgrade in southern China

To relieve the increasing traffic load, many early built highways need to be widened or reconstructed. The rapid performance detection to existing subgrades is important to their reasonable evaluation and maximized utilization. Based on five kinds of soils taken from an existing highway in southern China, three commonly detecting methods were used to determine their moisture contents, compaction degrees and resilient moduli. The results showed that the measured moisture contents were greater than the design value, and the compaction degrees decreased sharply compared to the original ones. The moisture and heat exchange produced a decrease in the resilient modulus of plate loading test(PLT) from the standard 60 MPa down to 40 MPa. Afterwards, the portable falling weight deflectometer(PFWD) and dynamic cone penetrometer(DCP) were used to evaluate the subgrade performances. The measured PFWD moduli and the DCP penetration rates were correlated with the resilient moduli of PLT, deflections of the Beckman beam test, compaction degrees and moisture contents. The correlation analysis indicates that both of two methods are suitable in rapid detecting subgrade performances, but PFWD method is more recommended for it has higher accuracy and efficiency.