木片水分与牛皮纸浆料强度特性的研究

四川成都木材综合厂生产牛皮纸,以混合木片为原料。每年四季所用木材的水分变化范围很大,原有工艺不合理,致使成纸合格率低。为此我们研究了木片水分对浆料强度的影响。 本试验应用表观重度法测定水分,该方法简易、快速,测定误差小,符合生产上的要求。 经实验得出了木片水分在45％以下时以及在50％～65％时适宜的蒸煮条件。经过半年多的生产实践,产品一级一等品合格率已稳定在80％以上,并取得了前所未有的经济效益。

木片水分与牛皮纸浆料强度特性的关系

四川省成都木材综合厂以混合木片为原料生产牛皮纸。每年四季所用木材的水分变化范围很大,原有工艺不合理,致使成纸合格率低。为此我们研究了木片水分对浆料强度的影响。经实验得出了木片水分在(?)5％以下及在50％～65％时适宜的蒸煮条件。经过半年多的生产实践,产品一级一等品合格率已稳定在80％以上,并取得了前所未有的经济效益。

采用高浓臭氧漂白 生产高强度浆料 降低废水排放

位于斯洛伐克的Mondi Business Paper SCP纸厂,为提高制浆生产能力和浆料质量,并降低对环境的影响,对整个制浆生产线进行改造并增加OxyTrac氧脱木素和ZeTrac臭氧漂白。本文介绍了改造前后的工艺流程、改造的效果与特点、生产线优化等。整个制浆生产线的改造由美卓负责,美卓提供了主要设备以及进行工程设计。

复合纤维素酶处理新闻纸浆的研究

用复合纤维素酶处理新闻纸浆,考察酶的作用条件,探讨最佳工艺条件下酶处理后还原糖生成量、纸浆滤水性及强度的变化规律.结果表明,酶在55.0℃、pH值为5.0时活力最高;Cu2+、Fe3+、Mn2+对酶活力影响不大;提高浆浓、缓慢搅拌能使酶解反应加快.在最佳作用条件下,纸浆加酶3-5IU·g-1(CMC酶活力)、处理1-2h,纸浆的打浆度下降4-5°SR,而酶解损耗、纸浆强度受影响不大.

搅拌站污泥用于泡沫混凝土掺合料的研究

混凝土搅拌站污泥难以有效利用,严重污染了周边环境。在分析污泥粒度和活性的基础上,采用污泥作为掺合料制备超轻泡沫混凝土。试验结果表明,污泥的比表面积可以超过1000m^2/kg,活性指数可以接近70%,因此可以用污泥作为掺合料用于制备超轻泡沫混凝土。随着污泥掺量的增加,超轻泡沫混凝土浆体稠度也逐渐增大,浆体稳定性也逐渐增强;掺加适量污泥有利于细化超轻泡沫混凝土孔径,提高孔的均匀度;制备超轻泡沫混凝土时,污泥的适宜掺量10kg/m^3~30kg/m^3,即污泥在胶凝材料中的用量为5%~15%,可以获得干密度160kg/m^3~180kg/m^3的超轻泡沫混凝土,其抗压强度达到0.5MPa。

Mechanical properties of anti-seepage grouting materials for heavy metal contaminated soil

Cement-based composite grouting materials were used to construct grouting cutoff wall for heavy metal contaminated soil in non-ferrous metal mining areas. Cement, fly ash, and slag as principal ingredients were mixed with water glass in different ways to produce three composite grouting materials. In order to investigate the effect of water glass mixing ratio, Baume degree, fly ash and slag contents on the mechanical properties of the composite grouting materials, particularly their gel time and compressive strength, the beaker-to-beaker method of gel time test and unconfined compressive strength test were conducted. In addition, the phase composition and microstructure of the composite grouting materials were analyzed by the X-ray diffraction（XRD） and scanning electron microscope（SEM） techniques. The test results show that their gel time increases when water glass mixing ratio and Baume degree increase. The gel time increases dramatically when fly ash is added, but decreases slightly if fly ash is partly replaced by slag. When the mixing ratio of water glass is below 20%, their compressive strength increases with the increases of the ratio; when the ratio is above 20%, it significantly decreases. The compressive strength also tends to increase as Baume degree increases, and improves if fly ash and slag are added.

BTMP的特性及其在双胶纸中的应用

论文考察了游离度为90ml的BTMP纤维特性和浆料强度,探讨了磨浆对BTMP纸浆强度的影响,研究了BTMP的用量对双胶纸性质的影响,结果表明,BTMP抗张强度比较低,白度也不高;随着游离度的上升,BTMP松厚度上升、裂断长和耐破指数下降,但磨浆对撕裂指数影响不大;BTMP在双胶纸中使用,有利于提高成纸的松厚度、不透明度、挺度等指标,可以改善纸的印刷适性;但对于成纸的强度、表面强度以及平滑度有着负面的影响,故其应用比例以不超过25%为宜。

Effects of rheoforming on microstructures and mechanical properties of 7075 wrought aluminum alloy

It is economically advantageous to cast wrought aluminum alloys directly into near-net-shape components.The objective of the present work is to take advantage of the rheoforming with 7075 alloy to improve the competitiveness of this emerging technology in the manufacture of wrought aluminum alloy.High quality semi-solid slurry was produced,in which primary α(Al) presents in diameter of 62 μm and shape factor of 0.78 and features no eutectics entrapped.Higher forming pressure results in small grain size,improved shape factor and higher density.Especially,rheoforming can effectively reduce the occurrence of hot tearing.The average yield strength and elongation of the rheoformed samples in the T6 condition are 483 MPa and 8%,respectively.

Effect of waste concrete with different strength on mechanical properties of recycled fine aggregate mortar

The influence of source concrete (SC) with different compression strengths on the workability and mechanical properties of recycled mortar made with river sand substituted by 100% fine recycled concrete aggregates (FRCA) is experimentally investigated. The basic physical performance test shows that with the increase in SC strength, FRCA exhibit lower water absorption and crushing index, meanwhile keeping higher densities. Mechanical property tests, including compressive strength, flexural strength and uniaxial compressive stress-strain tests, show that compressive strength,flexural strength and elasticity modulus of recycled sand mortars increase roughly with the increase in SC strength. The proposed mixture design method demonstrates that all of the components can be kept as the same as those in natural mortar mixture design and FRCA must be pre-wetted before making mortar mixture. Meanwhile, the reuse of higher strength SC can ensure that recycled mortar mixtures are able to achieve similar mechanical performance when compared to natural mortar designs.

Bonding between Aggregates and Cement Pastes in Concrete

This investigation was carried out to study the effect of aggregate roughness on ITZ （interfacial transition zone） at same water/cement ratio and the influence of silica fume on the bond strength. On the experimental side, two types of aggregates （limestone and granite） were used, which were prepared with broken surface. Cement （Type I） was used with same w/c ratio for all batches. In order to study the effect of silica fume on the bond, the same mixes were produced with 8% silica fume. Three different tests were performed： ＂pull a part＂, Brazilian test and compressive strength test. The specimens for Brazilian and compressive strength were tested after 28 days, while the ＂pull a part＂ specimens were tested after 29 days. The result showed that the bond strength is influenced by the surface roughness of aggregate. For the same mix, limestone recorded higher bond strength than granite. Moreover, the bond strength is increased by adding the silica fume.