共查询到20条相似文献,搜索用时 156 毫秒
1.
2.
采用筛分法、透气法和激光粒度法测试了不同细度铁铝酸盐水泥的颗粒特征参数,并对不同方法测试结果进行了对比分析,研究了细度对水泥物理性能的影响。结果表明:铁铝酸盐水泥勃氏比表面积与激光粒度法计算比表面积之间具有良好的线性关系,激光粒度法计算筛余与负压筛测定筛余结果之间没有对应关系。不同细度铁铝酸盐水泥颗粒符合RRSB分布,勃氏比表面积与特征粒径与均匀性系数的乘积之间呈幂函数关系。铁铝酸盐水泥凝结时间随细度增加而减小,强度随细度增加而增加,凝结时间及强度与比表面积之间具有良好的对应关系。 相似文献
3.
4.
5.
6.
主要研究了活性α Al2 O3微粉和水泥加入量对刚玉质浇注料性能的影响。结果表明 :随着微粉用量增加 ,浇注料的流动性和抗渣性改善 ,凝结时间缩短 ,抗热震性降低 ;随着水泥用量增加 ,流动性降低 ,凝结时间缩短 ,高温处理后的常温抗折强度降低 ,抗折强度保持率增加 ,抗渣性恶化。 相似文献
7.
通过对不同掺量稻壳灰(RHA)/粉煤灰(FA)和纳米SiO2 (NS)水泥基试样比表面积、需水量、凝结时间和水泥胶砂强度的测试,讨论了RHA/FA和NS掺量对水泥比表面积、需水量、凝结时间和胶砂强度的影响.结果表明,掺加RHA/FA会增大水泥比表面积,引起需水量的增大,延长水泥初、终凝时间,适量掺加NS会降低水泥比表面积,缩短水泥初、终凝时间,当RHA/FA掺量为20%时加入2% NS,RHA/FA和NS对水泥浆的需水量及凝结时间影响不大;RHA/FA取代水泥后,水泥胶砂3d和28 d强度均有所下降,加入NS后,各龄期强度均得到提高,尤其是3d强度提高幅度较大.可以通过掺加NS来弥补RHA/FA的掺入所引起的早期强度降低,达到相同强度可以适当提高RHA/FA的掺量. 相似文献
8.
研究了化学合成高纯铝酸钙水泥的物理特 性,包括强度发展、凝结时间、水化结合水量和水化放 热特性,并与市售的以传统烧结法生产的水泥进行了 在典型耐火浇注料中的应用比较。结果表明:(1)化 学合成高纯铝酸钙水泥胶砂的强度发展快且充分,早 期强度高;(2)化学合成高纯铝酸钙水泥的水化放热 速率在水化2h时最大,放热快且放热量集中;(3)化 学合成高纯铝酸钙水泥的水化活性较高;(4)化学合 成纯铝酸钙水泥用于耐火浇注料中,浇注料表现出较 高的烘干强度,且浇注料的烧后强度等性能指标也与 用传统烧结水泥的大体相当。 相似文献
9.
据TaikabutsuOverseas报道,含氧化铝水泥浇注料正广泛应用于钢铁等高温工业,但其在烘干过程中由于水蒸气的快速蒸发会引起爆裂.造成耐火材料的损毁。研究选用了10种不同类型的水泥(A-J),其A12O3含量为50%~81%,主要的矿物相为CA、CAZ、LI。A,、a-Al。O。等,有效比表面积为0.7~4.7m‘·g-‘。利用不同配料组成的低水泥浇注料和铝尖晶石浇注料,制成十55mm。50mm的试样测试抗爆裂性,制成4Omm。40mm;<160mm的试样测试养护后和烘干后的强度,并改变养护时间和养护温度。试验结果表明:对于低水泥浇注料,加入氧化铝… 相似文献
10.
改性磷石膏用作水泥缓凝剂 总被引:5,自引:1,他引:5
选用磷渣配料生产的熟料,进行了改性磷石膏作水泥缓凝剂的试验,采用自制改性剂,并经过热处理,对磷石膏进行改性,对比了改性磷石膏和天然石膏作缓凝剂的使用效果,结果表明,与天然石膏要比自制改性剂并经煅烧工艺制得的改性磷石膏作缓凝剂,水泥凝结时间一致或稍有缩短,早期强度略低,强度增进率较高,水泥安定性合格,并提出了水泥中SO3含量的控制范围。 相似文献
11.
To increase the packing density of blended cement paste, a gap-graded particle size distribution (PSD) was theoretically deduced and modified according to the wet density of actual paste. Then experiments were conducted to validate the hypothesis of improvement of the properties of blended cements by the gap-graded PSDs proposed. The experimental results show that the gap-graded PSD resulted in a decreased water requirement and an increased packing density of blended cement paste, and modified gap-graded PSDs gave further effects. The heat of hydration of gap-graded blended cement pastes released slowly in the first 24 h and increased rapidly afterward. The microstructure of gap-graded blended cements was much more homogeneous and denser than that of reference blended cement, therefore both early and late mechanical properties of low clinker gap-graded blended cements were improved significantly and even higher than those of Portland cement. 相似文献
12.
Bengisu Yildirim Övül Kümbüloğlu Ahmet Saraçoğlu Nadin Al-Haj Husain 《Journal of Adhesion Science and Technology》2013,27(18):2047-2060
This study evaluated the effect various surface conditioning methods on the surface topography and adhesion of luting cements to zirconia. Zirconia blocks (N?=?25) were randomly assigned to five groups according to the surface conditioning methods: (a) No conditioning, control (CON), (b) tribochemical silica coating (TSC), (c) MDP-based zirconia primer (ZRP), (d) coating with nano aluminum nitride (ALN) (e) etching with Er: YAG laser (LAS). The conditioned zirconia blocks were further divided into five subgroups to receive the luting cements: (a) MDP-based resin cement (Panavia F2.0) (PAN), (b) 4-META-based cement (Super Bond) (SUB), (c) UDMA-based (GCem) (GCE), (d) bis-GMA based (Bifix QM) (BIF) and (e) polycarboxylate cement (Poly-F) (POL). Cements were applied in polyethylene moulds (diameter: 3?mm; height: 2?mm). The bonded specimens were first thermocycled for 5500 cycles (5–55?°C) and then adhesive interface was loaded under shear (0.5?mm/min). The data (MPa) were analyzed using 2-way ANOVA, Tukey’s and Bonneferroni tests (alpha?=?0.05). Regardless of the cement type, TSC resulted in significantly higher bond strength (p???0.05) (13.3?±?4.35–25.3?±?6.3) compared to other conditioning methods (2.96?±?1.5–5.4?±?5.47). Regardless of the surface conditioning method, no significant difference was found between MDP, 4-META and UDMA based cements (p?>?0.05) being significantly higher than those of bis-GMA and polycarboxylate cements (p???0.05). Failure types were frequently adhesive in all groups. Tribochemical silica coating provided superior bond results compared to other conditioning methods tested on zirconia especially in conjunction with UDMA- and 4-META-based resin cements. 相似文献
13.
《Ceramics International》2016,42(12):13790-13795
The aim of this study was to evaluate Y-TZP surface pretreatment with different protocols on microshear bond strength (μSBS) ceramic-cement interface. One hundred and sixty pre-sintered IPS e-max ZirCAD (Ivoclar-Vivadent) blocks were randomly divided into sixteen groups according to surface treatment (n=20): G1- no treatment (control); G2- ceramic primer; G3- tribochemical silica coating; G4- tribochemical silica coating+primer; G5- airborne particle abrasion (Al2O3); G6- airborne particle abrasion (Al2O3)+primer; G7- Er,Cr:YSGG laser; G8- Er,Cr:YSGG laser+primer. All specimens were sintered before surface treatment, except lasers groups, which were sintered after laser irradiation. Ceramic blocks were bonded with Panavia F resin cement (Kuraray, Okayama, Japan) (n=10) or RelyX ARC (3M ESPE, St. Paul, MN, USA) (n=10). The μSBS tests were carried out in a universal testing machine at a speed of 1mm/min after 24 h (n=5) or 6 months storage (n=5). Differences were found for both resin cements and storage conditions in relation to μSBS values (p<0.05). However, no significant difference for interaction between factors was observed in cemented blocks with RelyX ARC. Panavia F resin cement showed significant differences for interaction between factors (p<0.05). Laser treatment was not sufficient to increase μSBS values between Y-TZP and resin cements. Tribochemical silica coating followed by primer achieved the highest immediate μSBS values. The storage did not affect negatively μSBS values to both evaluated cements. 相似文献
14.
《Journal of Adhesion Science and Technology》2013,27(5):535-552
Sandwich laminates containing re-formed bamboo core and aluminium face sheets were produced using two different types of adhesive: an epoxy and a modified polyethylene. The interlaminar fracture behaviour of the laminates was characterized based on peel and lap-shear tests. It was shown that the laminates bonded with polyethylene had much higher peel and shear strengths than those bonded with epoxy. For the polyethylene-bonded laminates, the major failure mechanisms were a combination of cohesive and interfacial failure, whereas for the epoxy-bonded laminates, the fracture occurred almost exclusively along the aluminium/epoxy interface. There was a significant dependence of the failure mechanism and interlaminar strength on the loading direction relative to the bamboo fibre axis and on whether the aluminium sheets were bonded to the inner or outer bamboo surface. 相似文献
15.
The rates of chloride diffusion from seawater into concrete made with different w/c ratios and different types of cements were studied. The effect of cathodic protection on the chloride penetration was also investigated. The effect of w/c ratio on the chloride content was limited mainly to a surface layer of the concrete and to short durations of exposure. For longer durations of exposure and for greater depths of penetration, cement type had a greater influence on the depth of chloride penetration than the w/c ratio. Portland cements gave as much as two to five times higher chloride penetration than blended cements. For the Portland cements as much as 8.6% C3A was not adequate for reducing the chloride penetration compared with zero-content of C3A. It appears that the diffusion of chloride ions into concrete is dependent not only on the permeability and the capacity of chloride binding but also on the ion exchange capacity of the system. 相似文献
16.
《Journal of Adhesion Science and Technology》2013,27(14):1931-1948
The wedge test was used to determine the durability of adhesively bonded joints of pretreated aluminium alloy AA6060 in a hydrothermal environment. Testing of joints bonded with the one-component epoxy adhesive XD4600 showed that the durability was higher for surfaces that were grit-blasted with alumina than for alkaline etched, FPL-etched, and sulphuric acid anodised surfaces. All these surfaces performed much better than those abraded with ScotchBrite®. It was discovered that increased surface roughness improved the durability, while increased surface contamination reduced the durability of the bonded joints. On a very rough surface such as the grit-blasted, the effects of surface contamination were more than outweighed by the effects of surface roughness. Treatment of some of the pretreated surfaces with a 1% aqueous solution of γ-glycidoxypropyltrimethoxysilane significantly improved the durability, but the ranking between the pretreatments was the same as before the silane treatment. The silane treatment also reduced the initial crack lengths of the wedge test specimens. The best performance was seen by the grit-blasting plus silane treatment, which performed much better than the well-established FPL-etch. 相似文献
17.
High intakes of Cr, Ni, and Zn in clinker: Part II. Influence on the hydration properties 总被引:1,自引:0,他引:1
This work presents the results of the hydration of cements with high intakes of Cr, Ni, and Zn. The cements were produced from clinkers that were doped with 200 to 25,000 ppm of heavy metal. Investigations on the clinkers were presented in Part I. In this paper the rate of heat generation of the cements in the first 2 days was analysed by differential scanning calorimetry. The hydration products were investigated by scanning electron microscopy combined with energy-dispersive X-ray spectrometer and also by X-ray powder diffraction. The initial setting of some samples was tested, as well as the strength. The results show that heavy metals only have an influence on the hydration properties of the cements if the dosage is much higher than in ordinary Portland cement. 相似文献
18.
María Lobato Sergio Santos del Riego Javier Montero María Isabel Orellana José Antonio Mirón Antonio Castaño 《Journal of Adhesion Science and Technology》2013,27(6):598-612
Objectives: The purpose of the study was to evaluate the effect of adhesive application on the shear bond strength (SBS) of orthodontic brackets and tubes to acid-etched human enamel when using different cementing agents. Study Design: One hundred and sixty metal attachments (80 tubes and 80 brackets) were bonded to human third molars and premolars that were randomly divided into identical groups of four: Transbond XT (XT); Wave MV Flow (WF); APC Plus System (APC); and Fuji Ortho LC (LC). For each experimental group, half of the specimens were bonded in combination with Transbond XT adhesive. After 72?h, a SBS test was performed using a universal testing machine. Statistical analysis was performed using ANOVA with Bonferroni post hoc comparisons, χ2 tests, and linear regression modeling. Adhesive remnant index scores were determined for the teeth after failure. Representative tooth surfaces from each subgroup were assessed under SEM. Results: Considering that each cement was observed, each of them showed similar SBS when the adhesive system was applied as when the adhesive was not applied. By comparing all cements together, it was noted that if an adhesive is not applied, all cements have similar values. If an adhesive is applied, cement XT, WF, and APC showed significantly higher SBS values than LC did. The tubes showed higher SBS than the brackets did in cements XT and WF with or without an adhesive, as well as APC Plus with an adhesive. Conclusions: The use of an adhesive system in bonding brackets and tubes does not influence the SBS obtained, independently of the cement. 相似文献
19.
Zeynep Duymus Yesil 《International Journal of Adhesion and Adhesives》2009,29(4):352-355
To investigate the microtensile bond strength (μTBS) and failure mode of resin cements bonded to ceramic blocks following various surface treatments.Seventy-two Ceramco II (Ceramco lnc., Burlington, NJ) ceramic discs 10 mm in diameter and 4 mm thick were prepared. The ceramic specimens received 8 different surface conditions treatments before the application of resin cement. These surface treatments were sanding with 600-grit silicon carbide paper, microetching with aluminum oxide, sanding followed by silane application, microetching followed by silane application, hydrofluoric acid etching, hydrofluoric acid etching followed by silane application, application of adhesive resin, and combination of the previous two treatments (HF+S+Adh). Seventy-two extracted molars were ground flat at 90° to the long axis of the tooth until a sufficient circular area of dentin was exposed (at least 5 mm in diameter). Three resin cements were applied to these surfaces. After 24 h storage at 37 °C, the non-trimming version of μTBS test was used to produce 1 mm2 microbars. The microbars were subjected to a tensile load using a modified testing device.Data were analyzed with 2-way analysis of variance. The interaction between the substrate surface treatment and cement type is significant (p<0.001).The results of this in vitro study suggest that when the tested ceramic restoration is cemented with a resin cement system, the ceramic should be etched with hydrofluoric acid, silane and adhesive should be applied prior to cementation. The results also suggest that an auto- or light-polymerizing cement should be considered instead of a dual-polymerizing cement. 相似文献
20.
《Journal of Adhesion Science and Technology》2013,27(4):343-362
Samples of polyethylene and polypropylene have been submitted to repeated short duration (75 ms) flame treatments, at optimum flaming conditions. Surface energies of untreated and flamed specimens were determined by liquid contact angle measurements. It appears that the surface energy of polyethylene increases much more than that of polypropylene after flame treatment. The flamed polymer surfaces were further examined by electron spectroscopy, Fourier Transform IR spectroscopy and secondary ions mass spectrometry. The adhesion properties of modified polymer surfaces were studied by testing in peel the bonded Styrene Butadiene Rubber/polyolefins assemblies. Scanning electron microscopy (SEM) and water contact angle measurements have been used to observe the locus of failure. Good correlations were obtained between surface energy and adhesion strength, the increase in adhesion strength being particularly important for flamed PE/SBR assemblies. In addition, the peeling in a liquid medium allowed the determination of the respective contribution to adhesion of chemical and physical interactions. It is shown that a major part of the adhesion strength increase is of chemical origin, particularly for the bonded flamed PE/SBR assemblies. 相似文献