负温公路用压浆料的研究与工程应用

研究了在负温环境条件下使用的公路用压浆料的最佳配比。通过单因素试验和正交试验研究了高铝水泥、聚羧酸减水剂、酒石酸、硼酸对压浆料流动性、凝结时间、强度的影响;通过复掺试验研究了碳酸锂、硝酸钙对其流动性、强度的影响,并确定了各组分最佳掺量。结果表明,复配的负温公路压浆料流动性好,无泌水及下沉现象,强度满足应用要求。该负温公路压浆料施工性能良好,现场取样实测Cl-和SO3含量、流动度、凝结时间及3、7、28 d强度均符合JTG/T 3650—2020《公路桥涵施工技术规范》要求。

基于Burgers模型的温拌胶粉沥青胶浆低温流变特性

为了研究热氧老化作用对SDYK表面活性剂型温拌胶粉改性沥青胶浆(SWCRM)和EM降黏剂型温拌胶粉改性沥青胶浆(EWCRM)低温流变特性的影响,对热氧老化后的SWCRM、EWCRM以及热拌胶粉改性沥青胶浆(HCRM)进行弯曲梁流变(BBR)试验.以劲度模量(S)与蠕变速率敏感指数(m)的比值S/m及基于Burgers模型的松弛时间(λ)和低温综合柔量参数(J_(c))为指标,分析老化作用对3种沥青胶浆低温流变特性的影响.结果表明:3种沥青胶浆热氧老化后的低温流变性能均减弱;采用Burgers模型研究沥青胶浆的低温流变性能是合理的;J_(c)能很好地描述沥青胶浆的低温流变性能;在-18℃时,EWCRM的S/m值和J_(c)值相较于HCRM分别下降了12.72%、8.58%,SWCRM的S/m值和J_(c)值相较于HCRM分别下降了30.09%、20.71%,说明温拌剂的加入会改善沥青胶浆的低温流变性能,且SDYK的改善效果优于EM.

泡沫温拌沥青胶浆的流变特性及微观机制分析

为了全面探究泡沫温拌沥青(以下简称泡沫沥青)胶浆的流变特性,分别针对不同粉胶比的泡沫沥青胶浆进行温度和频率两种扫描模式下的动态剪切流变(DSR)和弯曲梁流变(BBR)试验,分析了粉胶比对泡沫沥青胶浆高、低温性能的影响,利用van Gurp Palmen(vGP)图分析了泡沫沥青胶浆时温等效原理的有效性,基于此建立了泡沫沥青胶浆在频率扫描模式下的主曲线,并运用此主曲线分析了其在较宽的温度和频域下的流变特性。此外,通过扫描电子显微镜(SEM)的微观结构识别和差示扫描量热(DSC)的热特性测试分析了泡沫沥青胶浆的微观机制。结果表明:矿粉的添加对泡沫沥青的高、低温性能均有显著影响,随着粉胶比的增大,泡沫沥青胶浆的高温性能逐渐增强,低温性能逐渐降低;泡沫沥青胶浆适用于时温等效原理,在较宽的温度域及频率域内,泡沫沥青胶浆较基质沥青胶浆具有更优的高温性能。此外,泡沫沥青胶浆与基质沥青胶浆的低温等级温度基本一致;泡沫沥青胶浆中矿粉的分散性优于基质沥青胶浆中矿粉的分散性,且泡沫沥青胶浆中含有更多的微孔洞;基质沥青较泡沫沥青具有更好的热稳定性,但在相同的粉胶比下,泡沫沥青胶浆较基质沥青胶浆具有更好的热稳定性;粉胶比不大于1.0时,泡沫沥青胶浆较基质沥青胶浆具有更高的玻璃化转变温度。综合流变特性及微观机制分析得到泡沫沥青胶浆的粉胶比不宜大于1.0。

温拌沥青胶浆高温性能研究

为确定各种因素对温拌沥青高温性能的影响,文章基于DSR试验研究投料次序、沥青类型、温度及粉胶比对温拌沥青胶浆性能的影响。结果表明:投料次序对温拌沥青胶浆性能影响不大,室内温拌沥青胶浆可通过分次投料后采用玻璃棒搅拌制备;沥青类型对温拌沥青胶浆性能影响明显,温拌改性沥青胶浆的高温性能更佳;高粉胶比的温拌沥青胶浆具备更好的抗车辙能力;温度对温拌沥青胶浆的流动性能影响显著。

温拌沥青胶浆流变性能研究

为了研究温拌沥青胶浆流变性能,通过动态剪切流变试验,研究了投料顺序、温拌剂类型、温拌剂掺量、沥青类型和粉胶比等因素对温拌沥青胶浆流变性能的影响规律。研究结果表明:矿粉与温拌剂的添加顺序对温拌沥青胶浆的流变性能基本没有影响;Sasobit降低了温拌沥青胶浆的流变性能,3G提高了其流变性能;随着温拌剂掺量的增大,沥青粘度的增加和粉胶比的增大,温拌沥青胶浆的流变性能显著降低。

Effects of slurry pack cementation temperature on microstructure and wear resistance of Ti-Al co-deposited coating on copper plated nickel layer

In order to improve the wear resistance properties of copper substrate, a layer of electroplated nickel was firstly deposited on copper substrate, subsequently these electroplated specimens were treated by slurry pack cementation process with a slurry pack cementation mixture composed of TiO2 as titanizing source, pure Al powder as aluminzing source and also a reducer for titanizing, an activator of NH4Cl and albumen （egg white） as cohesive agent. The Ti-Al coating was fabricated on the surface of electro-deposited nickel layer on copper matrix followed by the slurry pack cementation process. The effects of slurry pack cementation temperature on the microstructures and wear resistance of Ti-Al coating were studied. The results show that the microstructure of the coating changed from NiAl＋Ni3（Ti,Al） to NiAl ＋Ni3（Ti,Al）＋Ni4Ti3 to Ni4Ti3＋NiAl, and to NiAl＋Ni3（Ti,Al）＋NiTi with slurry pack cementation temperature ranging from 800 ℃ to 950 ℃ in 12 h. The friction coefficient of Ti-Al coating decreased and the hardness increased with increasing the slurry pack cementation temperature. The minimum friction coefficient was 1/3 and the minimum hardness was 5 times larger than that of pure copper.

基于DIC技术的老化作用下温拌胶粉改性沥青胶浆低温抗裂性能研究

沥青胶浆对沥青混合料性能具有重要影响。为研究热氧老化作用对温拌胶粉改性沥青胶浆(WCRM)低温抗裂性能的影响,以热拌胶粉改性沥青胶浆(HCRM)作为对比试件,采用数字图像相关(DIC)技术对单边切口弯曲梁试验(SENB)中2种试件的开裂全过程进行图像采集,利用Vic-3D软件计算加载过程中试件的水平应变,从宏细观相结合的角度定量分析沥青胶浆的抗裂性能。对比分析沥青胶浆的荷载-位移(L-D)曲线和水平应变-时间(Exx-t)曲线,通过在细观尺度下胶粉改性沥青胶浆裂纹萌生和发展的规律来解释沥青胶浆宏观力学行为。通过弯曲梁流变试验(BBR)分析老化前后WCRM和HCRM的低温流变性能,并对沥青胶浆低温性能评价指标进行相关性分析。结果表明:随热氧老化程度的加深,HCRM和WCRM的水平应变密度DE值(细观层面)和临界断裂韧度JIC值(宏观层面)均减小,证明热氧老化会降低2种胶粉改性沥青胶浆的抗裂性能;相同条件下,WCRM的DE值和JIC值均大于HCRM,即与HCRM相比,WCRM具有更好的抗开裂和抗老化性能;在沥青胶浆开裂过程中,微裂纹形成时的荷载、峰值荷载及最大水平应变对应荷载并非同一荷载值;老化后,2种胶粉改性沥青胶浆的低温流变性能降低,同一条件下,WCRM具有更加优异的低温流变性能;沥青胶浆低温流变参数(S/m)与宏细观开裂指标(JIC,DE)均具有较好的相关性,即将DIC技术应用到SENB试验来分析老化作用及温拌剂对胶粉改性沥青胶浆宏细观开裂特性的影响具有较好的可靠性。

有光纸匀度质量的控制

纸张的匀度不仅是纸张外观质量的重要指标,而且匀度的好坏也影响到纸张的多项物理指标,如裂断长、耐破度、耐折度、紧度、吸收性、适印性以及光泽度等。对于有光纸匀度更有一定要求,如若匀度不好必然厚薄不一,纸面不平整,在干燥后会反映出光泽度不一致,而且纵横拉力比大,导致产品质量不合格。 要抄造匀度好的纸张,一定要使上网的纤维分布均匀。这与浆料的性质(如原料配比和打浆工艺)以及上网前浆料的流动状态,也就是浆的浓度与流速。

Effect of holding time on microstructure of Mg-9Al-1Si alloy during semisolid isothermal heat treatment

The effects of isothermal holding time on the semisolid microstructure of Mg-9Al-1Si(mass fraction,%)alloy were investigated.The research results indicate that the Mg-9Al-1Si alloy with non-dendritic microstructure can be produced by the semi-solid isothermal heat treatment.With holding time varying from 5 to 30 min,the volume fraction of liquid is gradually enlarged from 29.3%to 38.6%,the morphology ofα-Mg grains changes from initial dendritic shape to spherical types and their average sizes increases from 41.1 to 56.1μm.In addition,during the isothermal heat treatment,the eutectic Mg2Si phase changes from the initial Chinese script shape to granule and/or polygon shape in Mg-9Al-1Si alloy.The modification of Mg2Si phase is possibly attributed to a shift of the eutectic composition of the liquid in semi-solid slurries,towards lower silicon contents with increasing Al content due to a redistribution of Al during isothermal heat treatment.

Hydration phase and pore structure evolution of hardened cement paste at elevated temperature

To understand the effect of steam curing temperature on the hydrate and microstructure of hardened cement paste,several measuring methods including X-ray diffraction(XRD),atomic absorption spectroscopy(ASS),ion chromatography,conductivity meter,alternating-current impedance spectroscopy and nuclear magnetic resonance(NMR)are employed to investigate the hydration characteristics,pore solution composition and conductivity,resistivity and pore structure during the steam curing process.Experimental results show that steam curing promotes the hydration process,greatly raises the resistivity,and decreases the porosity of specimen at early age.Compared with being treated at 45℃,higher temperature leads to a fast decomposition of ettringite at initial stage of the constant temperature treatment period,which improves the relative content and ionic activity of the conductive ions in pore solution.Furthermore,the number of pores larger than 200 nm increases significantly,which reduces the resistivity of the hardened cement paste.Cement paste treated at 45℃ has a more stable and denser microstructure with less damages.

Rheological behavior of Shengli coal-solvent slurry at low-temperatures and atmospheric pressure

We report the results from systematic studies of Shengli lignite coal-solvent slurries. Solvent type, temperature, coal to solvent ratio, particle granularity, shear rate and shear time were investigated. The viscosity of the solvents is time independent. However, the slurries are thixotropic. A change from pseudo-plastic to Newtonian behavior occurs as the temperature, or as the solvent to coal ratio, increases. The solvent used in the slurry affects the point at which the rheology changes from pseudo-plastic to Newtonian. The REC slurry changes at 1:1.2 coal to solvent ratio and at 40 °C. The HAR slurry changes at a 1:1.5 ratio and at 60 °C. The rheology of the slurries is pseudo-plastic at low shear rates but Newtonian at high shear rates.

STUDY ON THE INFLUENCE OF WETTING HEAT ON COAL SLURRYABILITY

Wetting Heat of various ranks of coals in water was measured by using SETARAM C80D Calorimeter. The data were correlated to coals' slurryability which is characterized by the solid load at the viscosity of 1 Pa's and 25℃. The results showed that the heat of wetting by wa-ter decreases as coal rank increases in the range of brawn coal to bituminous coaI with carbon content of 89% ~90% (daf), and then, increases a little for anthracite. This trend fitted well to the relationship of slurryability to coal rank. The heat of wetting was also correlated to the inher-ent moisture content and the oxygen content of coal, which are commonly considered as slurrya-bility indication parameters. Hence, the wetting heat is another measure of coal's slurryability.

Gas-Liquid Mass Transfer in a Slurry Bubble Column Reactor under High Temperature and High Pressure

The gas-liquid mass transfer of H2 and CO in a high temperature and high-pressure three-phase slurry bubble column reactor is studied. The gas-liquid volumetric mass transfer coefficients kLa are obtained by measuring the dissolution rate of H2 and CO. The influences of the main operation conditions, such as temperature, pressure, superficial gas velocity and solid concentration, are studied systematically. Two empirical correlations are proposed to predict kLa values for H2 and CO in liquid paraffin/solid particles slurry bubble column reactors.

Influence of melt pouring temperature and plate inclination on solidification and microstructure of A356 aluminum alloy produced using oblique plate

The preparation of semisolid slurry of A356 aluminum alloy using an oblique plate was investigated. A356 alloy melt undergoes partial solidification when it flows down on an oblique plate cooled from underneath by counter flowing water. It results in continuous formation of columnar dendrites on plate wall. Due to forced convection, these dendrites are sheared off into equiaxed/fragmented grains and then washed away continuously to produce semisolid slurry at plate exit. Melt pouring temperature provides required condition of solidification whereas plate inclination enables necessary shear for producing semisolid slurry of desired quality. Slurry obtained was solidified in metal mould to produce semisolid-cast billets of desired microstructure. Furthermore, semisolid-cast billets were heat treated to improve surface quality. Microstructures of both semisolid-cast and heat-treated billets were analyzed. Effects of melt pouring temperature and plate inclination on solidification and microstructure of billets produced using oblique plate were described. The investigations involved four different melt pouring temperatures (620, 625, 630 and 635 °C) associated with four different plate inclinations (30°, 45°, 60° and 75°). Melt pouring temperature of 625 °C with plate inclination of 60° shows fine and globular microstructures and it is the optimum.

Residue Upgrading in Slurry Phase over Ultra-fine NiMo/γ-Al_2O_3 Catalyst

In this article, residual oil hydroconversion was studied in slurry phase in the presence of fine solid Ni Mo/γ-Al2O3 catalyst and the effects of operating conditions were carefully studied. The results showed that residue conversion was only affected by the reaction temperature and reaction time. The coke yield increased with a higher reaction temperature, a bigger catalyst particle size, a longer reaction time, a lower initial hydrogen pressure and a lower catalyst concentration. Heteroatoms removal rate increased with a higher reaction temperature, a longer reaction time, a higher initial hydrogen pressure, a higher catalyst concentration, and a smaller catalyst particle size. The role of catalyst in the slurry bed technology was discussed and its function could be stated as follows: the metal was applied to activate the hydrogen atoms for removing heteroatoms and saturating aromatics, while the support of the catalyst was used to prevent the mesophase coalescence for reducing coke formation.

Isothermal coarsening of primary particles during rheocasting

The isothermal coarsening behavior of primary solid particles in A356 aluminum alloy semi-solid slurry produced by angular oscillation (AO) technique was investigated.The comparison between the calculation and experimental results shows good quantitative agreement with Lifshitz-Slyozov-Wagner theory.The results show that the variation in shape factor and solid fraction is not significant,the average particle size increases with increasing holding time at the expense of the particle density.Ostwald repining is most likely the predominant growth mechanism in the AO-treated semi-solid slurry during rheocasting.The differences of coarsening occurred in rheocasting and partial re-melting process were also discussed.

Development of experimental study on coupled heat and moisture transfer in porous building envelope

A new facility was presented which can expediently and cheaply measure the transient moisture content profile in multi-layer porous building envelope.Then,a common multi-layer porous building envelope was provided,which was constructed by cement mortar-red brick-cement plaster.With this kind of building envelope installed in the south wall,a well-controlled air-conditioning room was set up in Changsha,which is one of typical zones of hot and humid climate in China.And experiments were carried out to investigate the temperature and moisture distribution in multi-layer building envelope in summer,both in sunny day and rainy day.The results show that,the temperature and humidity at the interface between the brick and cement mortar are seriously affected by the changes of outdoor temperature and humidity,and the relative humidity at this interface keeps more than 80% for a long-term,which can easily trigger the growth of mould.The temperature and humidity at the interface between the brick and cement plaster change a little,and they are affected by the changes of indoor temperature and humidity.The temperature and humidity at the interface of the wall whose interior surface is affixed with a foam plastic wallpaper are generally higher than those of the wall without wallpaper.The heat transfer and moisture transfer in the envelope are coupled strongly.

Validation of Analytical Method of Irbesartan Plasma in Vitro by High Performance Liquid Chromatography-Fluorescence

Irbesartan is an antihypertensive drug whose concentration in blood is very small so it requires a sensitive method of analysis, selective and valid for analysis. In this study, it is carried out optimization of analytical conditions and validation for the analysis of irbesartan in plasma. Chromatography was performed on a C 18 column （250 × 4.6 mm, 5 μm） under isocratic elution with acetonitrile-0.1% formic acid （46：54 v/v）, pH 3.75. Detection was made at excitation 250 nm and emission 370 nm and analyses were run at a flow-rate of 1.0 mL/min at a temperature of 40 ℃. Losartan potassium was used as internal standard. Plasma extraction was done by deproteination with acetonitrile, mixed with vortex for 30 seconds, then centrifuged it at 10,000 rpm for 10 rain. In plasma validation, the recovery was 96.22%, and the lower limit of quantification （LLOQ） in plasma was 2 ng/mL. The method also fulfill the criteria for accuracy and precision intra and inter day by normal values （%Diff） not exceed ± 15%. On the stability study, irbesartan in plasma temperature -20 ℃has been stable for 28 days.

Preparation,Structure Characterization and Hydrodesulfurization Performance of B-Ni_2P/SBA-15/Cordierite Monolithic Catalysts

A series of B-Ni2P/SBA-15/cord monolithic catalysts were prepared by coating the slurry of the B-Ni2P/SBA-15 precursors on a pretreated cordierite support, and followed by temperature-programmed reduction in a H2 flow. The samples were characterized by X-ray diffraction （XRD） and N2 adsorption-desorption technique. The catalytic activities for the hydrodesulfurization （HDS） of dibenzothiophene （DBT） were evaluated. The results showed that Ni2P phase was present in all B-Ni2P/SBA-1 5/cord monolithic catalysts. The specific surface areas （SBET） of the B-Ni2P/SBA-15/cord monolithic catalysts was first increased to 167 m2· g-1, and then decreased to 155 m2· g-1 with the increase of boron contents. The catalytic activity also showed the similar trend with the increase of boron contents. The 1.75% （by mass） B-Ni2P/SBA-15/cord monolithic catalysts exhibited the highest DBT conversion of 98.4% at 380 ℃. The cordierite-based monolithic catalysts showed better low temperature sensitivity for HDS of DBT in comparison with the particle catalysts. Moreover, two HDS routes, direct desulfurization （DDS） and hydrogenation （HYD）, proceeded independently over B-Ni2P/SBA-15/cord monolithic catalysts and the main pathway was DDS.

Study on Properties of Anti-Gas Channeling Lightweight Temperature-Resistant Latex Slurry

There is low formation pressure coefficient and high formation temperature in ludong-wucaiwan area. Gas cut and gas channeling happen seriously during oil and gas well cementing. The existing anti-migration additive has only effects on single trait, so it is difficult to meet cementing requirement. According to this situation we could use latex slurry to anti-gas channeling. We have synthesised a set of anti-gas channeling lightweight temperature-resistant latex slurry and formed a new channeling preventing latex slurry through plenty of previous laboratory experiments. Finally the performance of latex slurry on temperature-resistant, anti-gas channeling and the anti-gas channeling of cement paste are studied. The experimental results show that this latex system has strong temperature-resistant and anti-gas channeling, which completely meet the requirement of cementing in this area.