矾土基浇注料基质的流变性

浇注料的流变性在很大程度上受基质流变行为的影响和控制。本工作主要研究了矾土基浇注料基质中的SiO2微粉、Al2O3微粉、水泥的加入量、分散剂以及矾土细粉粒度对基质流变性(粘度、剪切速率和剪切应力)的影响根据研究结果,得出了具有较好流变性的基质组成。     

养护时间对不同结合体系的刚玉基浇注料性能的影响

为了研究养护时间对不同结合体系的刚玉基浇注料性能的影响,以致密电熔刚玉颗粒(粒度有5~3、3~1、≤1 mm)、致密电熔刚玉细粉(粒度≤0.044 mm)、α-Al2O3微粉、硅灰、电熔镁砂细粉(粒度≤0.088 mm)、纯铝酸钙水泥以及工业纯高效分散剂三聚磷酸钠等为主要原料,设计了4种不同结合体系(分别为无水泥、超低水泥、低水泥和水泥结合)的刚玉基浇注料,主要研究了养护时间对浇注料脱模、烘干及分别在1 300和1 600℃煅烧3 h后的常温耐压强度和烧后线变化率的影响。结果表明:无水泥浇注料须养护1 d以上,超低水泥和低水泥浇注料需养护3 d以上才可获得较好的物理性能,水泥浇注料的最佳养护时间为3 d。     

转炉出铜沟用新型环保浇注料的研制

为了改善出铜沟用耐火材料的结构剥落和合理利用钛铁渣,以钛铁渣(8~5、5~3、3~1、≤1和≤0. 074mm),88高铝矾土(≤1 mm),SiO2微粉(5~3μm),活性α-Al2O3微粉(5~3μm),CA-80水泥(44~20μm)和蓝晶石微粉(≤0. 045 mm)为主要原料,探讨了颗粒级配(q为0. 25、0. 26、0. 27、0. 28、0. 29和0. 30)对浇注料性能的影响,并在最佳颗粒级配(q=0. 26)的基础上研究了蓝晶石加入量(w)为0、2%、4%、6%和8%时对浇注料高温体积稳定性的影响。结果表明:(1)采用钛铁渣为主要原料的转炉出铜沟用浇注料,当粒度分布系数q=0. 26时,浇注料的颗粒级配最佳,流动性和各项常温性能最好。(2)蓝晶石加入量为4%(w)时,出铜沟浇注料的高温性能最佳;蓝晶石的莫来石化可改善浇注料的使用性能。(3)转炉出铜沟用新型环保浇注料的显气孔率低,体积密度大,高温烧后强度有大幅提升,且原料成本低,实现了资源的循环利用。     

微粉对矾土基超低水泥浇注料性能的影响

以高铝矾土熟料为主原料 ,加入 2 %的铝酸钙水泥及总量为 6 %的Al2 O3 微粉和SiO2 微粉 ,配制了矾土基超低水泥浇注料 ,研究了微粉对浇注料的烧结性能、力学性能及热震稳定性的影响。结果表明 :(1 )SiO2 微粉对浇注料的促烧结作用优于Al2 O3 微粉。这是因为与Al2 O3 微粉相比 ,由气相沉积生成的SiO2微粉的粒度小 ,比表面积大 ,活性较高。 (2 )随着SiO2微粉加入量的增加 ,在 1 1 0 0℃和 1 4 0 0℃处理后的常温强度以及在 1 30 0℃和 1 4 0 0℃下的高温抗折强度和抗热震性明显提高。这是由于引入的SiO2 微粉在高温下与Al2 O3 反应生成的针状莫来石穿插进入刚玉骨架 ,起着明显的强化和韧化作用     

β-SiAlON加入量对刚玉基超低水泥浇注料流变性的影响

以矾土基电熔刚玉为骨料,电熔白刚玉粉、αAl2O3微粉、SiO2微粉、纯铝酸钙水泥和矾土基β-SiAlON为基质,固定骨料和基质的质量比为68∶32,水泥加入量(质量分数,下同)2%,SiO2微粉和Al2O3微粉总加入量为8%,分别用0、4%、6%、8%和10%的β-SiAlON替代刚玉细粉,加水混匀后制成刚玉基超低水泥浇注料。用浇注料流变仪研究了βSiAlON加入量对此浇注料流变性(包括扭矩、流动阻力和粘度)的影响,结果表明:随βSiAlON加入量的增加,在变化的剪切速率下,刚玉基浇注料的扭矩、剪切粘度和流动阻力增加,流变性变差,自流浇注所需加水量增加,流动性降低。综合考虑,合适的β-SiAlON加入量为4%～6%。     

刚玉质自流浇注料流变性和流动性的关系

以电熔白刚玉、SiO2微粉、α-Al2O3微粉、纯铝酸钙水泥和Alphabond为原料配制刚玉质自流浇注料,用全组分浇注料流变仪和L型流动性测试装置,研究了不同种类和加入量的微粉(加入SiO2微粉质量分数6%～8%或α-Al2O3微粉质量分数1%～4%)、1%～4%的结合剂(纯铝酸钙水泥或Alphabond)对自流浇注料流变性和流动性的影响。结果表明:(1)随着SiO2微粉和α-Al2O3微粉加入量的增加,刚玉质自流浇注料的剪切扭矩和相对塑性黏度下降;自流值随SiO2微粉加入量的增多而增大。(2)水泥加入量的变化对刚玉质自流浇注料流变性和流动性的影响很小;随Alphabond加入量的增加,剪切扭矩和相对塑性黏度显著增大,而自流值呈增大的趋势。(3)刚玉质自流浇注料的流变性与流动性之间存在一定的关系:相对塑性黏度与自流时间T30有较好的线性相关性,而与自流值无明显关联。     

结合系统对刚玉基浇注料常温断裂行为的影响

为揭示结合系统对刚玉基浇注料常温断裂行为的影响,以板状刚玉颗粒、板状刚玉细粉、α-Al2O3微粉、Si O2微粉、纯铝酸钙水泥和水合氧化铝为主要原料,通过改变基质中纯铝酸钙水泥的加入量(加入质量分数分别为0、1%、3%和5%),制备了低水泥、超低水泥和无水泥刚玉基浇注料,采用楔入劈拉法研究了刚玉基浇注料的断裂行为。结果表明:结合体系的不同显著改变了浇注料的断裂行为。低水泥和超低水泥刚玉基浇注料的载荷-位移曲线呈线性,属典型的脆性断裂,表明浇注料的韧性差。无水泥刚玉基浇注料的载荷-位移曲线呈非线性,属准稳态断裂,说明浇注料的韧性高。含水泥浇注料中结合相为玻璃相或钙长石,玻璃相多且连续分布导致浇注料呈脆性。而在无水泥浇注料中,结合相为针柱状莫来石,玻璃相少且孤立分布于莫来石形成的网络中,有利于韧性的提高。     

粒度组成对Al2O3-SiC-C浇注料气孔特性的影响

以电熔刚玉(8～5、5～3、3～1、≤1、<0.088 mm)、碳化硅(≤1 mm)、球状沥青(1～0.5 mm)、硅粉(<0.088 mm)、SiO2微粉、Al2O3微粉为原料,铝酸钙水泥为结合剂,通过改变粒度分布系数q(分别为0.21、0.22、0.23、0.24、0.25),制备了不同粒度组成的Al2O3-SiC-C浇注料,并研究了q对110℃24 h烘干和1 450℃3 h埋炭烧后浇注料试样显气孔率、透气度和孔径分布的影响。结果表明:当q由0.21增大到0.25时,烘干和烧后浇注料试样的显气孔率和透气度均先减小后增大,当q=0.23时显气孔率最小,而q=0.22时透气度最小;烘干后试样的平均孔径随q的增大而增大,而烧后试样的平均孔径却没有明显的规律;对于烘干和烧后试样的孔径分布而言,当q为0.21、0.22及0.25时具有明显的离散性,而当q为0.23和0.24特别是q=0.23时,则孔径趋于集中连续分布。     

添加高纯SiO_2微粉对Al_2O_3-SiC-C铁沟料性能的影响

以棕刚玉、碳化硅、铝酸盐水泥、氧化铝微粉等原料制备Al_2O_3-SiC-C质铁沟浇注料,对比研究了普通SiO_2微粉与高纯SiO_2微粉对浇注料性能的影响。结果表明:1)高纯SiO_2微粉杂质含量极低,其体积平均粒径仅为普通SiO_2微粉的10%,比表面积比普通SiO_2微粉高50%。2)在铁沟浇注料使用高纯SiO_2微粉可以促进铁沟浇注料凝固,降低铁沟浇注料的需水量,提高铁沟浇注料的成型致密度、常温强度、高温强度、抗渣性能和实际使用寿命。     

氧化铝微粉与减水剂对刚玉质浇注料施工性能的影响

研究了减水剂(包括六偏磷酸钠和萘系、三聚氰胺类及聚羧酸盐类3类减水剂)、氧化铝微粉(包括烧结氧化铝微粉和活性氧化铝微粉)对纯铝酸钙水泥结合刚玉质浇注料的流动性能和力学性能的影响。结果表明:1)氧化铝微粉的平均粒度对浇注料的流动度有较大的影响,在一定范围内,粒度越粗,浇注料的初始流动性越小,可工作时间越短。2)氧化铝微粉中可溶性碱性氧化物的含量对浇注料的施工性能和可工作时间有一定的影响。3)减水剂既影响浇注料的需水性,还影响浇注料的强度发展,必要时需引入缓凝剂或者促硬剂进行调节。4)综合比较萘系、三聚氰胺类及聚羧酸盐类3类减水剂,以聚羧酸盐类减水剂的减水效果较好。     

Influence of hydroxypropylguars on rheological behavior of cement-based mortars

Hydroxypropylguars (HPGs) are used as water retention agents in modern factory-made mortars. Nevertheless, these molecules can also impact the rheological behavior of cement-based materials. The influence of HPG and its dosage on mortar rheological properties was thus investigated thanks to a suitable measurement procedure. HPG allows keeping a positive yield stress value while the yield stress of hydroxypropyl methyl cellulose (HPMC) mortars was found to decrease with an increase in dosage. HPG increases the shear-thinning behavior and the consistency of mortars. The study of pore solution viscosity suggests that the entanglement of HPG coils beyond a threshold dosage is crucial to understand the rheological macroscopic behavior of HPG-admixed mortars. Nevertheless, the increase in mortar viscosity induced by HPG was lower than expected which reveals additional and specific repulsive forces induced by polysaccharides.     

超声辐照前后煤浆粒度分布变化研究

选用红会、大同及兖州煤制备水煤浆,考察了超声辐照前后煤浆粒度分布变化,并研究了超声辐照前后粒度分布变化对煤浆表观粘度、流变物质及静态稳定性影响,在超声辐照强度为８０Ｗ／ｃｍ＾２,频率为２０ｋＨｚ的条件下,超声辐照导致煤浆中１００μｍ以下的细级煤粒的比例明显增加,实验结果表明,超声辐照对煤浆具有很强的分散作用,在一定的粒度范围,细级煤粒的增加有利于煤浆流变性能的改善,同时细级煤粒的增加是煤浆静态 稳     

Rheological Behavior of the Matrixes of Bauxite-Based Castables

Rheology of castables is greatly affected and cantrolled by rheological behavior of their matrix,In this work,the rheological properties of bauxite-based castable matrix have been studied.The effecfts of super-fine silica and alumina addition,water/cemenl ratio,dispersants and baurite particle-size on viscosity,shear rate and shear stress of the slurries have been investigated.Based on these results,the range of optinium composition of the matrix with good rheological behavior has been obtained.     

Unique shape memory behavior of polyolefinic blends with special reference to creep behavior,stress relaxation,and melt rheological study

Creep response, stress relaxation behavior, and melt rheological study of the shape memory polymer blend based on EOC‐EPDM has been studied in details. In this study, especially the effect of the crosslinks formation in presence of electron beam on the creep response, melt rheological study and stress relaxation behavior has been reported. With increase of electron beam dose, creep response becomes lower and the creep compliance value also comes down. Higher resistance creep response of the radiation crosslinked blends indicates the superior shape recovery behavior of the blends. Stress relaxation behavior of the crosslinked blend also shows the lower decay of stress value with time for higher radiation crosslinked blend. The lower relaxation ratio of the highly radiation crosslinked blend also supports the superior shape recovery behavior of the crosslinked blend. Apart from, melt rheological study shows the higher storage modulus value and higher complex viscosity of the radiation crosslinked blend which also supports the formation of higher crosslinked network structure. Tension set value also clearly indicates the better shape recovery behavior of the crosslinked blend. POLYM. ENG. SCI., 58:876–885, 2018. © 2017 Society of Plastics Engineers     

Rheological properties of alcohol-coal suspensions based on Ukrainian coals of different ranks

The rheological behavior of alcohol-coal suspensions based on coals of different ranks prepared with the use of lower alcohols from the methanol-propanol series as a dispersion medium was studied. It was found that an increase in the length of an alkyl radical leads to an increase in the shear stress and viscosity of the alcohol-coal suspensions. In this case, the suspensions obtained with the use of isoalcohols are characterized by lower viscosity than the suspensions obtained with the use of normal alcohols. From the dependence of the shear stress and viscosity of alcohol-coal suspensions on the physical properties of lower alcohols, it follows that an increase in the dynamic viscosity and dipole moment, as well as a decrease in the dielectric constant (with increasing the length of the hydrocarbon radicals of alcohols), leads to an increase in the above rheological parameters.     

EFFECT OF OSMOTIC DEHYDRATION ON VISCOELASTIC PROPERTIES OF APPLE AND BANANA

The rheological behavior of osmotically dehydrated apple and banana was examined under uniaxial compression and relaxation tests of cylindrical specimens. Compression and relaxation tests were performed, following air drying of osmotically pre-treated samples, at various moisture contents ranging from 0.1 to 1.5 kg/kg dry basis. The maximum stress and the corresponding strain were correlated to the moisture content using simple mathematical equations. It was shown that both parameters increase as water was removed and their values are significantly higher than the corresponding values for untreated air dried samples. The effect of moisture content on compressive behavior of osmotically dried materials was introduced through its effect on the four model parameters: the maximum stress (σ_max) the maximum strain (ε_max), the elastic parameter (E) and the viscoelastic exponent (p). The stress relaxation data of osmotically treated samples were modeled using a two-term Maxwell model. It was shown that osmotic pre-treatment increased the remaining force and it decreased the relaxation time of dehydrated samples. The osmotic dehydration and therefore the sugar gain tend to increase the viscous nature of fruits and decrease their elasticity for both materials, causing plasticity of the structure.     

水焦浆的流变特性与壁面滑移效应

在浆体流动试验系统上采用不同管径的直管考察了水焦浆的流变特性以及壁面滑移效应对水焦浆流动特性的影响。采用Tikhonov 正则化方法确定了水焦浆的真实流变特性和壁面滑移特性。结果表明：浓度为59.8%的水焦浆随剪切速率增大呈现由伪塑性流体到胀塑性流体的转变,浓度增加,水焦浆变为单一的胀塑性流体,当浓度达到63.4%时,水焦浆表现为由胀塑性流体到伪塑性流体的转变;水焦浆的流变特性对滑移速度的变化趋势具有较大影响,滑移速度在水焦浆为胀塑性流体时随剪切应力增加呈加速增加,水焦浆为伪塑性流体时滑移速度随剪切应力的增长速率变化不明显;滑移贡献率的变化趋势迟滞于流变特性曲线。     

Effects of sucrose on the rheological behavior of wheat starch pastes

The rheological properties of starch–water–sucrose pastes have been determined under steady and oscillatory shear conditions. The results show that the effect of sucrose at concentrations of less than about 20% w/w is to increase the apparent viscosity, yield stress, dynamic viscosity, and dynamic rigidity. At higher surose concentrations the yield stress and dynamic rigidity tend to zero while values of the dynamic viscosity and apparent viscosity are reduced compared with controls. Sucrose causes the dispersed gel particles in pastes to change volume, and it is suggested that this is one of the factors responsible for the observed effects of sucrose on rheological behavior.     

超细粉体对水泥净浆流变行为影响研究

采用截锥圆模法测定不同掺量超细粉体水泥复合浆液的流动度.采用ZNN-D6B型旋转黏度计研究超细玻璃粉和偏高岭土两种超细粉体对水泥净浆流变行为的影响,得到了剪切速率-剪切应力(γ-τ)曲线和剪切速率-表观粘度(γ-μa)曲线,并分别采用宾汉姆模型和赫-巴模型对γ-τ流变曲线进行拟合,得到不同掺量超细玻璃粉-水泥(GP-C)复合浆液和偏高岭土-水泥(MK-C)复合浆液的动切力、塑性粘度、稠度系数和流性指数等流变参数.结果表明:超细粉体的加入降低了复合浆液的流动度.随着掺量的增加,两种复合浆液的宾汉动切力τ0、塑性粘度η、赫-巴动切力τy均逐渐增大,MK-C复合浆液的稠度系数K和流性指数n逐渐减小,GP-C复合浆液的稠度系数K呈现增大-减小-增大的趋势,而流性指数n呈现减小-增大-减小的趋势.所有样本表观粘度μa都随着剪切速率的增大而减小,呈现剪切稀释现象.     

RHEOLOGICAL BEHAVIOR OF LOW-RANK COAL-WATER SLURRIES

The rheological behavior of low-rank coal-water slurries was studied using a Brookfleld Rheolog viscometer. A Sarpy Creek subbituminous coal from Montana, with particle sizes ranging from 0.044 mm to 0.223 mm, was used. The solids concentration in the slurry varied from 15 to 65 weight % and the temperature was maintained constant at 82°F. The rheological behavior of the slurry made from as received coal was compared with that of the slurry made from hot water dried coal

Coal-water slurries, made from both as received and hot water dried coal exhibited pseudoplastic behavior. The shear stress was found to be related to the shear rate by the power law model. As expected, the apparent viscosity was found to increase sharply with solids loading. It was also observed that the apparent viscosities of the slurries made from hot water dried coal were lower than those made from as received coal.