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研究了不同温度处理对磷酸钾镁水泥性能的影响,并利用X射线衍射仪、综合热分析仪、扫描电子显微镜对机理进行了分析。试验结果表明,在100℃以上的高温环境下,磷酸钾镁水泥质量会减少、强度会发生降低;物相分析的结果显示,高温处理后磷酸钾镁水泥的主要水化产物Mg KPO4·6H2O衍射峰会降低;热重分析的结果显示,磷酸钾镁水泥试样在108℃左右有一个明显的吸热谷并伴随着明显的质量损失;微观形貌分析的结果显示,经高温处理后磷酸钾镁水泥的水化产物减少,过烧氧化镁会大量裸露。磷酸钾镁水泥经高温处理后性能下降是水化产物在高温下分解导致的。 相似文献
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针对碳纤维片材加固混凝土结构所用有机胶软化点过低的问题,研制了具有一定耐高温性能,可用于碳纤维粘结的氯氧镁胶凝材料。本文完成了60块不同层数(2、4、6、8层)的氯氧镁胶凝材料粘结碳纤维板在20~400℃高温后的拉伸性能试验。通过对试验结果的分析,研究了碳纤维板的层数及所经历温度对高温后氯氧镁胶凝材料粘结碳纤维板的残余抗拉强度及弹性模量等的影响。试验结果表明,常温下,采用MOC粘结碳纤维板抗拉强度与采用有机胶浸渍碳纤维板相当;经300℃高温处理后的氯氧镁胶凝材料粘结碳纤维板抗拉强度仍可以保持其常温下抗拉强度的70%左右,但是400℃后,碳纤维板抗拉强度迅速下降,仅为常温下抗拉强度的35%左右;随着温度的升高,高温处理后的碳纤维板弹性模量逐渐降低。 相似文献
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本文提出了一种简单有效的预氧化处理方法,用来强化反应烧结碳化硅(RBSC),研究了800~1 300 ℃预氧化处理对其微观结构和力学性能的影响,探究了含不同尺寸压痕裂纹的材料在氧化前后残余弯曲强度的变化规律。结果表明,随着氧化温度的升高,RBSC的室温强度和Weibull模数均存在先下降后上升,然后再下降的趋势,主要原因是不同温度氧化后的RBSC表面形貌不同。在1 200 ℃下预氧化2 h,RBSC的弯曲强度和Weibull模数都明显变大,强度提升了19.9%,Weibull模数由7.3提升到11.8。然而,800 ℃低温氧化不完全和1 300 ℃高温氧化反应过于强烈均会导致弯曲强度和Weibull模数下降。在最优氧化条件(1 200 ℃氧化2 h)下,含压痕裂纹(载荷20 N)的RBSC试样的残余弯曲强度在氧化后由201.1 MPa提高到324.2 MPa,强化机理是高温氧化生成的SiO2能够消除材料表面缺陷和微裂纹。 相似文献
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为了研究磷酸钾镁水泥基材料与硅酸盐水泥混凝土的粘结性能,测试了磷酸钾镁水泥基材料浆体的抗压强度,同时测试了磷酸钾镁水泥基材料浆体与不同状态的硅酸盐水泥砂浆的粘结抗折强度和收缩变形,分析了磷酸钾镁水泥基材料硬化体的物相组成、微观形貌以及与硅酸盐水泥砂浆基体的粘结界面结构.结果表明:双掺粉煤灰和石灰石粉,使磷酸钾镁水泥基材料硬化体的结构更完善,抗压强度、粘结抗折强度和体积稳定性均明显提高.保持硅酸盐水泥砂浆基体的龄期大于7d和气干含水状态,磷酸钾镁水泥基材料与硅酸盐水泥砂浆界面的结合力加强,粘结抗折强度明显提高. 相似文献
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研究高温下不同炭黑用量的氢化丁腈橡胶(HNBR)的回弹值、邵尔A型硬度、拉伸强度、拉伸应力松弛性能和动态力学性能等,分析温度对橡胶分子链段和物理交联网络等微观运动和微观结构的影响。结果表明:随着温度从25℃升高至150℃,不同炭黑用量的HNBR硫化胶的邵尔A型硬度和拉伸强度逐渐减小,回弹值先增大后减小,应力松弛速率增大,应变扫描前后储能模量之差减小;炭黑用量越大,高温下HNBR硫化胶的拉伸强度保持率越大,应力松弛的平衡应力占比越小;温度升高会破坏炭黑补强HNBR硫化胶的填料网络结构,导致结合胶含量减少,HNBR硫化胶高温下的力学性能下降。 相似文献
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《中国陶瓷工业》2020,(2)
以板状刚玉、ρ-Al_2O_3和硅微粉为主要原料,外加适量的铝酸钙水泥、水玻璃和氧化镁,制备得到一种可在室温固化的Al-Si系高温粘结剂材料,表征了不同温度烧成后材料的力学性能和微观结构。结果表明:材料经1300-1500℃高温烧成后,主要物相为镁铝尖晶石、氧化铝和Al_(1.66)Ca_(0.68)Na_(0.3)O_8Si_(2.34)。随着烧成温度的提高,材料中液相逐渐减少,镁铝尖晶石和氧化铝的晶粒析出,晶粒形状更加规则。当烧成温度达到1600℃时,材料的主要物相为镁铝尖晶石和氧化铝,其弹性模量、抗折强度和耐压强度分别为37.85 GPa、34.46 MPa和54.84 MPa。 相似文献
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《涂料工业》2017,(3)
以青铜粉为颜料,环氧改性有机硅树脂为粘合剂,采用喷涂法制备了环氧改性有机硅/青铜复合涂层。研究了热处理温度及热处理时间对所制备涂层外观、微结构、红外发射率及力学性能的影响。结果表明:环氧改性有机硅/青铜复合涂层最高可耐300℃高温,在300℃下热处理5 h后,涂层外观、微结构保持不变,红外发射率低至0.228,力学性能保持完好,硬度、附着力和耐冲击性分别为4H、1级和50 cm。所制备涂层在250℃下可长时间使用,在250℃下热处理100 h后,涂层外观、微结构仍然保持不变,红外发射率可低至0.227,力学性能保持完好,硬度、附着力和耐冲击性分别为4H、1级和50 cm。 相似文献
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以低钙型粉煤灰为主要原料,硅酸钠和氢氧化钠为复合碱激发剂,硅烷偶联剂(KH550)为增强材料,硅丙乳液为辅助成膜物质制备地聚合物无机涂料。研究了硅烷偶联剂掺量、反应温度以及水固比对地聚合物无机涂料的成膜性、耐水性和耐洗刷性等性能的影响,并通过XRD、FTIR、SEM、TG-DSC分析了无机涂料的微观结构及其耐高温性能。结果表明,当制备温度为60 ℃、水固比为0.31(质量比)、硅烷偶联剂掺量为3.6%(质量分数)时,地聚合物无机涂料在室温下的成膜性良好,无开裂现象,涂料24 h内质量吸水率为1.84%,耐洗刷性可达12 000次,7 d时硬度为154 s。地聚合物无机涂层内部主要是无定形的硅铝酸盐凝胶,硅烷偶联剂经水解、键合生成簇状产物填充在涂层的孔隙之间,增加了涂层的密实性,抑制了裂纹的产生。涂层在25~800 ℃的失重率为12.0%~13.0%,未发现明显的地聚合物热分解现象,说明涂层耐高温性能良好。 相似文献
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Polysilazane coatings have a broad need in real-life applications, which require low processing or working temperature. In this work, five commercially available polysilazanes have been spin-coated on polycarbonate substrates and cured in ambient environment and temperature to obtain transparent, crack-free, and dense films. The degree of crosslinking is found to have a significant impact on the hardness and Young's modulus of the polysilazane films but has a minor influence on the film thickness and hydrophobicity. Among all five polysilazane coatings, the inorganic perhydropolysilazane-based coating exhibits the largest hardness (2.05 ± 0.01 GPa) and Young's modulus (10.76 ± 0.03 GPa) after 7 days of curing, while the polyorganosilazane-derived films exhibit higher hydrophobicity. The molecular structure of polysilazanes plays a key role in mechanical properties and hydrophobicity of the associated films, as well as the adhesion of coatings to substrates, providing an intuitive and reliable way for selecting a suitable polysilazane coating material for a specific application. 相似文献
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研究了无机钠盐和镁盐对聚氨酯注浆材料固化过程温度的影响,并研究了添加无机盐对材料阻燃性能、表面电阻及抗压强度的影响。结果表明,环境温度为35℃,添加聚醚组分1.2%(质量百分比)无机盐,注浆材料固化最高温度有不同程度下降。其中,添加MgCl2时,注浆材料固化最高温度为102℃,与空白相比,下降了25℃。添加无机盐后,材料阻燃性能略有提高,表面电阻基本不变;抗压强度有所降低。热重分析表明,添加MgCl2时材料的热稳定性无明显改变,而添加其它无机盐,热稳定性有不同程度降低。 相似文献
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溶胶-凝胶/环氧杂化涂料的应用 总被引:1,自引:0,他引:1
溶胶-凝胶/环氧杂化涂料的配方已经进行了研究,杂化涂料具有更强的机械强度(如硬度),更加耐磨蚀。当固化温度提高到80℃,全部研究的杂化涂料都能通过湿性黏结试验,但在室温下固化时仅有部分的杂化涂料通过湿性黏结试验。多数杂化涂料在室温下固化时对水的敏感性问题尚待解决。 相似文献
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Epoxidized soybean oil-based ceramer coatings 总被引:3,自引:2,他引:1
New inorganic/organic hybrid coating containing epoxidized soybean oil were prepared. Three sol-gel precursors [titanium (IV)
i-propoxide, titanium (IV) di-i-propoxide bis-acetoacetonate, and zirconium n-propoxide] were utilized as the inorganic phase. Various coating properties, including adhesion, hardness, impact resistance,
flexibility and tensile properties, were investigated as a function of sol-gel precursor type and concentration. All ceramer
coatings exhibited excellent flexibility and hardness. Tensile strength and hardness increased with sol-gel precursor concentration.
A slight decrease in adhesion and impact resistance was observed with increasing precursor content. 相似文献
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Preparation and characterization of sol–gel derived UV-curable organo-silica–titania hybrid coatings
In this work, UV-curable organic–inorganic hybrid coatings based on cycloaliphatic epoxyacrylate were prepared by sol–gel technique. Acid catalyzed solutions of tetraethylorthosilane (TEOS) containing Ti:acac complex were used as an inorganic precursors. UV-curable, transparent hybrid coating materials were applied on plexiglass substrates and their coating performance was investigated by the analyses of various tests such as hardness, gloss, cross-cut adhesion tests, stress–strain test and optical transmission. The mechanical measurements showed that, the tensile properties of coatings underwent an abrupt change from a brittle to a tough material when the inorganic part was incorporated into the cycloaliphatic epoxy acrylate based organic network. UV–vis transmission spectroscopy results indicated that the hybrid materials with high titanium content have good transparences. The thermal behaviour of the coatings was also evaluated. It is observed that the thermal stability of the hybrids is enhanced with incorporation of sol–gel precursor. 相似文献
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Synthesis of fluorinated/methacrylated epoxy based oligomers and investigation of its performance in the UV curable hybrid coatings 总被引:2,自引:0,他引:2
Memet Vezir Kahraman Gülay Bayramolu Yaln Boztoprak Atilla Güngr Nilhan Kayaman-Apohan 《Progress in Organic Coatings》2009,66(1):52-58
Organic–inorganic hybrid coatings based on fluorinated/methacrylated soybean oil and bisphenol A/F epoxy methacrylate were obtained by combining photopolymerization and sol–gel process. Hard and transparent hybrid coatings were prepared on polycarbonate panels and their physical and mechanical properties such as gel content, hardness, adhesion, gloss, contact angle as well as tensile strength were measured. Results from the mechanical measurements showed that the properties of hybrid coatings improved with the increase in fluorine and sol–gel precursor contents. Thermo gravimetric analysis results demonstrated that fluorine and silica incorporations significantly enhanced the thermal oxidative stability of the hybrid coating materials. The surface morphology was also characterized by scanning electron microscopy (SEM). SEM studies indicated that inorganic particles were dispersed homogenously throughout the organic matrix. 相似文献