原位复合TiN/O′-sialon在空气中的氧化行为

通过对不同气孔率和TiN含量的原位复合TiN/O′-sialon材料在空气中的氧化行为研究,得出了不同材料在不同温度下的氧化结果,提出了不同材料在不同温度下的氧化机理和模型.     

TiN/O′-Sialon原位复合材料的抗氧化性能

通过对不同条件下原位复合制备的各种TiN/O′-Sialon材料在空气中的氧化行为研究,考查了氧化温度、气孔率和TiN含量对材料抗氧化性能的影响.结果表明:当氧化温度升高到一定值时,通常材料表层会形成致密的"保护膜",阻碍材料的进一步氧化;材料的气孔率和TiN含量越低,越易形成"保护膜",反之,越不易形成"保护膜".当材料的气孔率为30%以上,TiO2添加量为30wt%以上时,即使在更高的氧化温度下也不能形成"保护膜".     

原位复TiN／O‘—sialon在空气中的氧化行为

通过对不同气孔率和ＴｉＮ含量的原位复合ＴｉＮ／Ｏ’－ｓｉａｌｏｎ材料在空气中的氧化行为研究，得出了不同材料的不同温度下的氧化结果，提出了不同材料在不同温度下的氧化机理和模。     

常用涂层材料进展及超硬涂层技术

硬质涂层材料中,工艺最成熟、应用最广泛的是TiN。目前,工业发达国家TiN涂层高速钢刀具的使用率已占高速钢刀具的50%~70%,有的不可重磨的复杂刀具的使用率已超过90%。由于现代金属切削对刀具有很高的技术要求,TiN涂层日益不能适应。TiN涂层的耐氧化性较差,使用温度达500℃时,膜层明显氧化而被烧蚀,而且它的硬度也满足不了需要。TiC有较高的显微硬度,因而该材料的耐磨性能较好。同时它与基体的附着牢固,在制备多层耐磨涂层时,常将TiC作为与基体接触的底层膜,在涂层刀具中它是十分常用的涂层材料。TiCN和TiAlN的开发,又使涂层刀具的性能上了一个台阶。TiCN可降低涂层的内应力,     

TiN等离子体材料的研究进展

主要介绍了TiN等离子体材料概念,光学作用机制,并阐述了TiN在生物透明窗,太阳能传感器,光电转换及水氧化方面的进展。未来的TiN等离子体材料在生物领域、太阳能领域、净水领域及人工光合作用领域得到广泛应用。     

Al_2O_3晶须在Y-TZP/TiN(w)材料中作用机制的初探

本实验基于Y-TZP/TiN(w)复合材料存在高温下严重氧化致使材料破坏的现象,通过引入Al_2O_3晶须来改善该材料的高温抗氧化能力。实验采用聚乙二醇作分散剂预处理Al_2O_3晶须和TiN晶须,然后将其与用化学共沉淀法制得的Y-TZP粉料球磨均匀混合,通过热压烧结获得致密的烧结体。本文研究了不同的Al_2O_3晶须添加量对     

碳热还原氮化合成TiN的研究

以锐钛矿(中位径0.38μm)、金红石(中位径4.58μm)和鳞片石墨(粒度<0.15mm)、炭黑(平均粒度0.02μm)、可膨胀石墨(粒度<0.15mm)为原料,固定配比nC∶nTiO2为5∶1时分别组成不同的原料组合,并以锐钛矿和鳞片石墨为原料,改变配比nC∶nTiO2分别为3∶1、4∶1、5∶1、6∶1、7∶1和8∶1进行配料,在管式电炉、流动N2中分别于1300℃和1400℃制备了TiN,并进行了合成产物的氧化脱碳试验;采用XRD测定TiN的特征峰(d200=0.212nm)强度,以表征TiN的合成率,研究了原料粒度、反应物活性、反应温度等因素对TiN合成率的影响。结果表明:选用粒度较细或晶格活性大的原料,提高反应温度,均有利于提高TiN粉末的合成率;合成TiN粉末的最佳原料组合是可膨胀石墨和锐钛矿;以鳞片石墨和锐钛矿为原料时,其配比为nC∶nTiO2=6∶1时TiN合成率最高;合成产物中均含有一定量的碳,采用普通的加热氧化法不能除碳,其原因是TiN的氧化温度低于石墨的。     

Si3N4-TiN陶瓷氧化模型

氮化硅-氮化钛陶瓷的氧化行为是建立在对其微观结构的观察,对这种氧化模型现象进行了描述,并对其氧化动力学模型进行研究。当温度<1 000℃,只有TiN相被氧化。此氧化过程是由氧气通过TiO2扩散来控制的,由氧化动力学抛物线方程来描述。超过1 000℃的过程是非常复杂的,那是因为同时发生Si3N4和TiN相的两种氧化反应。三种氧化模型都被清晰的扩散机理所控制,是接连发生的。第1步,Si3N4和TiN相被独立的氧化,它们分别被氧化为SiO2和TiO2相。Si3N4的氧化是由氧通过SiO2扩散控制的,而TiN的氧化由钛通过TiO2扩散所控制。第2步,TiN的氧化被氧通过TiO2扩散控制,而通过SiO2被氧化形成Si3N4。第3步,TiN和Si3N4的氧化由氧通过二氧化硅层扩散控制。动力学方程可以由这三种氧化模型的任意一种决定。     

Si3N4-SiC材料的氧化性能研究

通过对不同Si3N4含量、不同温度下Si3N4-SiC材料的氧化实验,分析氧化后的氧化增重率,得出Si3N4含量越高,材料氧化越严重;氧化温度越高,材料氧化越严重;且氧化增重率与氧化时间呈直线-抛物线规律。     

TiN/O''''-Sialon原位复合材料的抗氧化性能

通过对不同条件下原位复合制备的各种TIN／O′Sialon材料在空气中的氧化行为研究,考查了氧化温度、气孔率和TiW含量对材料抗氧化性能的影响。结果表明：当氧化温度升高到一定值时,通常材料表层会形成致密的“保护膜”,阻碍材料的进一步氧化;材料的气孔率和TIN含量越低,越易形成“保护膜”,反之,越不易形成“保护膜”。当材料的气孔率为30％以上,TiO2添加量为30wt％以上时,即使在更高的氧化温度下也不能形成“保护膜”。     

氢气纯度分析方法准确性的探讨

ONACCURACYOFANALYSISOFOFHYDROGEN1前言我公司目前应用的氢气纯度分析方法有两种,一种是爆炸反应法,另一种是焦性没食子酸吸收法。几年来,人们对两种分析方法的准确性曾有过褒贬不一的评论。这里我们也谈谈自己粗浅的观点。2爆炸法测定氢气纯度一定量的氢气样品与适量的空气之均匀混合物因反应后生成液体水而引起气体体积减少,减少的体积等于参加反应气体体积之和。其中l／3为氧气,2／3为氢气。根据氢气取样量和反应前后混气体体积之差,以及氢气在反应中的体积比例关系,可计算出样品的氢气纯度。计算公式式中：A一混…     

COMPARISON OF METHODS OF ANALYSIS OF GYPSUM1

The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO₃ and determination of CaO by KMnO₄ titration, the SO₃ by Andrews method of titration of BaCrO₄ has been found to give very reliable results with the least consumption of time.     

SEDIMENTATION OF BINARY MIXTURES OF PARTICLES OF UNEQUAL DENSITIES AND OF DIFFERENT SIZES

A model is developed for the sedimentation from a suspension of two particle species of unequal densities and of different sizes. The composition and the thickness of various layers in the sediments are predicted using graphical and analytical methods. The model predictions were in excellent agreement with experimental results, when the particle size ratio was ≥ 108. When size ratio of the particles was 2.60 and 4.31 the agreement occurred in about 50 percent of the cases.     

HEASUREHENT OF INSTANTANEOUS RATES OF LOSS OF VOIATILE COMPOUNDS DURING DRYING OF DROPS

A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.

Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology.     

茶多酚提取方法进展

本文综述了国内外现有茶多酚提取方法的现状以及近期的研究进展，并对其优缺点进行了评价。这将有助于中低档茶的综合利用和茶多酚的进一步开发应用。     

几种针状焦性能对比

针状焦分石油系和煤系两大类,这主要取决于针状焦的原料来源。在同一系列中由于原料不同和工艺条件不同 ,针状焦的各自性能也不相同。针状焦是生产超高功率石墨电极和高功率石墨电极的主要原料 ,针状焦的性能对石墨电极的质量有至关重要的影响。所以对针状焦性能以及其对石墨电极质量影响的研究十分必要的。以下是常用的几种进口针状焦和国产针状焦的性能对比。１原料性能分析对比原料试样包括４种针状焦 ,其中两种为进口针状焦：三菱针状焦和新日化针状焦;另两种为国产针状焦：鞍山针状焦和锦州针状焦。其中除锦州针状焦是石油系针状焦外…     

ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES

Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log₁₀ viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log₁₀ viscosity as a function of soda content are smooth up to 50% Na₂O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO₂, 2Na₂O) due to Molecular Substitution of CaO, MgO and Al₂O₃ for Na₂O The effect is clearly brought out by plotting (from the results of English) the change of log₁₀η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature T_a. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log₁₀η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A1₂O₃) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al₂O₃) per 100°. At the aggregation temperature the change of log₁₀η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al₂O₃. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log₁₀η due to substitution of an oxide for Na₂O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na₂O-CaO-SiO₂. Change of Viscosity of Glass (4SiO₂, 2Na₂O) due to of Substitution of B₂O₃ for SiO₂ The change of log₁₀η (from the results of English) is plotted as a function of temperature, and also the change of log₁₀η per per cent B₂O₃. The curves are more complex than for the substitution for Na₂O.     

环氧树脂羟基值测定方法的研究

利用乙酸酐、吡啶和浓硫酸混合的乙酰化试剂测定环氧树脂中羟基值含量的方法具有操作简便、滴定终点明显和分析结果误差小等优点。     

骑式摩托车油箱喷涂工艺的改进

面对日益激烈的市场竞争,摩托车油箱外观质量越来越成为影响销售的因素之一。文章介绍了改进工艺后的油箱涂装,该涂装体系提高了油箱外观的丰满度,降低了油箱涂装的生产成本。     

聚酰亚胺的合成法

本文评述了缩聚型聚酰亚胺的主要合成方法和近年来国际上在合成中所做的探索。