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随着半导体工业的高速发展以及太阳能光电池产业的突起,对单晶以及多晶硅材料的需求不断增加。精密切割工具不仅要满足切割的质量,还要保证现代化生产的高效率。采用传统内圆锯片切割以及游离磨料多线锯切割逐渐显示出各种不足。而采用固着磨料多线锯切割是快速发展起来的一种精密切割技术。该文综述了固着磨料多线锯的锯丝制造方法,总结了固着磨料多线锯加工硬脆材料的锯切工艺,介绍了目前使用较多的多线锯切割机床,并展望了提高固着磨料多线锯锯丝寿命的可能途径。 相似文献
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本文采用圆轨迹法和改型马丁代尔法两种测试方法对不同织物起毛起球进行测试,研究不同方法、不同磨料对织物起毛起球的影响。 相似文献
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介绍磁性磨料研磨的加工原理及磁性磨料在磁场中的受力分析。对钢领的内、外跑道进行磁性磨料研磨加工的试验,得出了优化的磁性磨料研磨的加工参数。 相似文献
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采用渗硼淬火工艺对造锁模具进行强化,提高模具抗磨料磨损的能力。结果表明,用该工艺能使模具平均提高两倍以上。 相似文献
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Effects of formaldehyde/urea mole ratio and melamine content on the hydrolytic stability of cured urea-melamine-formaldehyde resin 总被引:1,自引:0,他引:1
The influence of formaldehyde/urea (F/U) mole ratio and melamine content on the hydrolytic stability
of urea-melamine-formaldehyde (UMF) resin was investigated. The hydrolytic stability of cured UMF resin
was determined by measuring the mass loss and the liberated formaldehyde concentration after acid hydrolysis.
A higher F/U mole ratio and greater melamine content of UMF resins resulted in lower hydrolytic stability.
These results indicated that higher F/U mole ratio and greater melamine content resulted in more branched
network structure, which subsequently increases the susceptibility of cured UMF resin toward acid hydrolysis. 相似文献
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The change of some chemical properties of UF-bonded particleboards was evaluated as a function of used resin modifier (melamine formaldehyde resin, resorcinol, tannin, PMDI) and the type of catalyst used (ammonium chloride,-sulfate,-nitrate, ammonium sulfate in combination with formic acid). The results reveal that with increasing amount of catalyst the pH value of the water extractives of UF-bonded boards decreases and their buffering capacity increases. Increasing the amount of catalyst above a certain limit may increase the emanation of formaldehyde from the particleboard under the conditions (40°C, 100% rel. humidity) used by the WKI-method. The type of the catalyst has a marginal influence on the pH value of the water extractives of UF-bonded boards. However, significant differences were found in the pH value of the water extractives of boards bonded with different UF-resins (UF 1 and UF 2). Modification of UF-resins with melamine resin and resorcinol increases the pH value of water extractives and decreases the buffering capacity of particleboards bonded therewith. Increasing the amount of resorcinol lowers the formaldehyde release, insofar it seems that the formaldehyde is involved in the modification process. Moreover, modification of UF-resins with melamine formaldehyde resin as well as resorcinol seems to reduce the release of volatile acids from the particleboards. The modification of the UF-resins with melamine resin and resorcinol increases the amount of free, still unreacted, urea in the resin. This phenomenon may be due to a reaction between modifier and formaldehyde leaving less free formaldehyde to react with urea. 相似文献
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The influence of formaldehyde/urea (F/U) mole ratio and melamine content on the hydrolytic stability
of urea-melamine-formaldehyde (UMF) resin was investigated. The hydrolytic stability of cured UMF resin
was determined by measuring the mass loss and the liberated formaldehyde concentration after acid hydrolysis.
A higher F/U mole ratio and greater melamine content of UMF resins resulted in lower hydrolytic stability.
These results indicated that higher F/U mole ratio and greater melamine content resulted in more branched
network structure, which subsequently increases the susceptibility of cured UMF resin toward acid hydrolysis. 相似文献
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目的对密胺餐具中三聚氰胺和甲醛迁移量进行调查研究,并对数据进行分析。方法在上海的企业和消费市场采集密胺餐具共40份,采用红外光谱法进行材料鉴别,依照GB 4806.7—2016《食品安全国家标准食品接触用塑料材料及制品》和GB 31604.1—2015《食品安全国家标准食品接触材料及制品迁移试验通则》进行迁移试验,测定三聚氰胺和甲醛迁移量。结果密胺餐具存在材质未标识、标识不清或标识有误的现象;脲醛树脂中三聚氰胺和甲醛的迁移量均高于密胺树脂,且迁出量与温度呈正相关。结论脲醛树脂应用于餐具存在风险,国家标准中有必要增加密胺材质鉴定检测方法。 相似文献
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采用聚乙二醇对三聚氰胺甲醛树脂进行改性,改性后的树脂用作交联剂添加到苯丙乳液中,并对汽车工业滤纸原纸进行浸渍加工处理。通过研究聚乙二醇(P)、三聚氰胺(M)、甲醛(F)的不同配比、树脂添加量及固化pH值,探讨了其作为乳液交联剂对汽车工业空气滤纸的抗张强度、耐破度、耐水性、透气度的影响。实验结果表明,当P与M的摩尔比为0.32,F与M-MP的摩尔比为2.8,改性树脂添加量为苯丙乳液固含量的4%,固化pH值为6~7时,汽车工业空气滤纸的综合性能最佳(苯丙乳液的上胶量为25%)。当pH值为6时,滤纸的抗张强度为4.51 kN/m,耐破度为340 kPa,耐水性为39.4min,透气度为334 L/(m2.s)。 相似文献
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E1级三聚氰胺改性脲醛树脂的研制 总被引:4,自引:0,他引:4
从中密度纤维板的甲醛释放机理和降低甲醛释放量的方法入手,设计出三聚氰胺改性脲醛树脂配方,并对三聚氰胺加入量、摩尔比、助剂和固化剂的选择进行探讨,用该树脂压制的中密度纤维板的各项理化性能指标均达到E1级要求。 相似文献
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目的 测定和分析网购密胺餐具的材质、高锰酸钾消耗量和脱色,研究迁移温度对甲醛迁移量的影响,评估网购密胺餐具的质量。方法 采集网上在售的18批次密胺餐具,通过衰变全反射(Attenuated Total Reflection) 红外法分析密胺餐具和脲醛餐具的特征吸收峰,快速区别密胺餐具和脲醛餐具。依据GB 4806.7-2016《食品安全国家标准 食品接触用塑料材料及制品》对密胺餐具高锰酸钾消耗量、脱色进行了测定和分析。依据GB 4806.6-2016 《食品安全国家标准 食品接触用塑料树脂》对密胺餐具的甲醛迁移量进行测定和分析。结果 脲醛餐具占样品总数44.4%,覆盖密胺涂层的脲醛餐具占样品总数33.3%;11.1%的样品高锰酸钾消耗量不合格;11.1%的样品4%乙酸浸泡液脱色不合格;11.1%的样品甲醛迁移量不合格(4%乙酸,70℃,2h)。结论 本次网上购买的密胺餐具高锰酸钾消耗量、脱色存在不符合GB 4806.7-2016的现象;甲醛迁移量不符合GB 4806.6-2016标准的现象,存在用脲醛餐具替代密胺餐具或是在脲醛餐具上覆盖密胺涂层以次充好的现象。 相似文献