SiC(N)/LAS吸波材料吸波性能研究

研究了由SiC(N)纳米吸收剂制备的SiC(N)/LAS吸波材料的介电性能,对影响介电性能的吸收剂的含量、吸波材料烧结温度和碳界面层等因素进行了较为全面的研究。结果表明,在1080℃以下烧结温度对陶瓷致密度的影响较大而对陶瓷介电常数的影响较小;在1080℃以上烧结温度对烧结致密度的影响较小,对陶瓷介电常数的影响较大,吸波材料介电常数的实测值与计算值之间存在很大的差异,这种差异是吸波材料制备过程中纳米级的SiC(N)促进了碳界面层形成,导致了在较高温度烧结时吸波材料介电常数对温度的敏感性,使吸波材料介电常数的实测值与计算值之间出现了很大的差异,形成的碳界面层复介电常数的虚部较高,使吸波材料对电磁波的损耗进一步升高,从而使吸波材料的吸波性能得到增强。     

热压条件对短切SiCf/LAS复合材料介电/力学性能的影响

采用热压烧结法制备出致密度超过90%的短切SiCf增强LAS玻璃陶瓷基复合材料,讨论了热压温度与压力对复合材料性能的影响。力学测试表明,当热压温度由1200℃上升到1280℃,复合材料断裂强度从124MPa下降到80MPa,断裂韧性从3.27MPa.m1/2下降到2.92MPa.m1/2;当热压压力由20MPa提高到34MPa,复合材料断裂强度从124MPa下降到86MPa,断裂韧性从3.27MPa.m1/2下降到3.00MPa.m1/2。断口形貌SEM观察结果表明,因纤维掺入过量,φ(SiCf)=36%,使纤维与基体结合较差;而过高的热压温度与压力会使界面反应加剧,破坏纤维强度及纤维与基体的结合。介电性能测试表明,在8～12GHz频率,复合材料复介电常数的实部ε′由基体的7.6增大到10～70,虚部ε″由基体的0.34增大到60～160,介电损耗tgδ由基体的0.04增大到2～20,并具有明显的频散效应。而且,随热压温度升高或者热压压力的增加,复合材料ε′增大,而ε″与tgδ减小。复合材料具有成为电损耗型宽带微波吸收材料的潜力。     

烷基苯磺酸钠在土壤中的吸附和降解行为(待续)

探讨了阴离子表面活性剂烷基苯磺酸钠(LAS)在不同土壤上的吸附行为,分析了LAS分子结构和土壤粒度、温度、盐度及pH等主要因素对LAS吸附量的影响,阐述了LAS在土壤中的降解机理,并分析了LAS分子结构、初始含量及环境中微生物数量、温度及pH等主要因素对LAS降解效率的影响,为以后LAS的扩大应用及其污染治理提供了充分的参考和依据。认为向土壤中排放LAS量会加大,污染程度会日趋严重,应着重消除影响LAS降解的环境限制因素,减少在土壤上的吸附量,最终解决LAS污染问题。     

SiC纤维／LAS复合材料的TG－DTA－MS研究

本文首次用ＴＧ－ＤＴＡ－ＭＳ联用技术对ＳｉＣ纤维／ＬＡＳ微晶玻璃复合材料的热分解过程、机制及其与晶化的关系进行了研究。提出了该复合材料界面形成碳层的热力学和质谱分析判别依据，并对晶化前后的复合材料的热分解行为作了实验对比和理论分析。     

混凝预处理洗浴废水中的LAS

以洗浴废水为研究对象,比较了铝盐、铁盐及有机高分子混凝剂对洗浴废水中的LAS去除效果,筛选出聚合氯化铝(PAC)作为混凝剂处理效果较好,进而采用单因素试验研究了混凝剂的投加量,废水的pH,静沉时间,搅拌强度和搅拌时间对LAS去除率的影响,结果表明PAC投加量为45mg/L,废水pH值为6.0～8.0,静沉时间为15min,中速(150r/min)搅拌3min,慢速(50r/min)搅拌10min时混凝效果最佳,对LAS的去除率达44.75%。     

Phthalates,nonylphenols and LAS in an alternately operated wastewater treatment plant--fate modelling based on measured concentrations in wastewater and sludge

The performance of an alternately operated activated sludge wastewater treatment plant (WWTP) has been investigated with respect to six phthalates, nonylphenol (NP) and nonylphenol diethoxylate (NPDE) and linear alkylbenzene sulphonates (LAS). Samples of raw sewage, primary and secondary sludge and treated water were collected during an 8-day period in May 1999 and analysed for dissolved and sorbed substances. To evaluate the system performance with respect to substance removal through biodegradation and sorption to sludge the measured data were applied in a model describing the different bioreactors as one single reactor, corresponding to the concepts of, e.g. SimpleTreat. The most abundant of the investigated phthalates was di-(2-ethylhexyl)-phthalate (DEHP) with a measured mean inlet flow of 240g/day. Two percent of this amount was found in the treated water, 70% was biodegraded and 28% was found in the sludge. For LAS the mean inlet flow was 20,300g/day, of which less than 1% was found in the treated water, 84% was biodegraded and 15% was found in the sludge. The mean inlet flow of NP and NPDE was 44 and 590g/day, of which 4% and 2% was found in the treated water, 80% was biodegraded for both substances, and 16% and 18% was found in the sludge, respectively. The WWTP removal of the investigated substances was thus high compared to other studies of conventional activated sludge WWTPs. The simple model set-up presents a strong tool for predicting substance removal and system sensitivity related to changes in the inlet conditions, such as concentrations and flow. Furthermore, it allows the inclusion of complex alternately operated WWTPs in risk assessment tools such as e.g. SimpleTreat.     

Properties of selective laser melted spodumene glass-ceramic

In this article, we established the process conditions and characterised the resulting properties of additively manufactured spodumene important for selective laser melting of LAS–Al₂O₃. X‐ray diffraction analyses revealed the as‐printed samples printed with layer thickness of 50 μm were fully crystalline. Energy dispersive X-ray spectroscopy showed that the major elements before and after the printing process were present and in similar quantity. Micro‐computerised tomography inspection also revealed layer thickness‐dependent pore formation in all printed samples. In terms of mechanical properties, the highest flexural strength measured using the three‐point bend test method was 4.33 MPa. More importantly, these results demonstrated that there is still potential in the direct laser melting of ceramics.     

含磷零膨胀LAS透明微晶玻璃的相转变动力学研究

以零膨胀Li2O-Al2O3-SiO2透明微晶玻璃为研究对象,采用示差扫描量热法（DSC）研究了无磷和含磷玻璃的析晶动力学和玻璃转变动力学行为．结果发现,引入少量的磷化物使得玻璃的析晶峰温度和玻璃转变温度降低,玻璃的析晶活化能和玻璃转变活化能增大,晶体生长指数n减小,使玻璃网络结构重排困难．     

形核条件对Li2O-Al2O3-SiO2玻璃晶化和性能的影响

通过差热分析(DTA)、X射线衍射分析(XRD)和扫描电镜(SEM)等方法，研究了形核条件对Li2O-Al2O3．SiO2(LAS)玻璃晶化和性能的影响。研究发现，当玻璃在最佳形核温度745℃形核2h和6h后，Avrami常数n为3．6和3．5，晶体生长激活能为276kJ／mol和280kJ／mol。这表明在此形核温度下，改变晶化时间对玻璃的晶化影响较小。当晶化温度发生变化，晶化条件为760℃／2h时，Avrami常数降低到2．8，晶体生长激活能增加到312kJ／mol。在850℃晶化后，均获得了h-石英固溶体为主晶相的微晶玻璃。SEM观察发现晶粒均为等轴晶粒，表明析晶方式均为体积析晶。但随形核温度偏离最佳形核温度，从745℃增加到760℃，晶化后样品的晶粒尺寸加大，同时强度硬度以及断裂韧度等性能下降。     

水中LAS的催化氧化处理研究

研究了催化剂ＺｎＯ／Ｎｉ２Ｏ３对水中十二烷基苯磺酸钠（ＬＡＳ）氧化降解的催化作用，并对影响催化氧化反应的因素进行了探讨，通过正交实验确定了最佳反应条件。实验表明，对浓度为２０ｍｇ／Ｌ的ＬＡＳ溶液，在氧化剂ＮａＣｌＯ加量为０．１ｍＬ／Ｌ，催化剂加量１．５ｇ／Ｌ、ｐＨ值为４时，经２ｈ催化氧化反应，其平均去除率达９３．８％。