1 mol/L盐酸溶液中酮康唑对Q235碳钢的缓蚀行为

抗真菌药物酮康唑(KCZ)可作为碳钢的缓蚀剂,目前有关其吸附机制尚不明确。采用失重法、电化学阻抗谱、电化学噪声(EN)和扫描电镜,系统研究酮康唑对Q235碳钢在1 mol/L盐酸溶液中的缓蚀行为。结果表明:酮康唑对Q235碳钢的缓蚀效率η随其浓度的增加而提高,其在Q235碳钢表面的吸附作用主要为化学吸附成膜,吸附过程遵循Langmuir吸附等温式;同时,酮康唑对Q235碳钢的缓蚀效率与Q235碳钢的活性反应能量具有相反的变化方向,因此可以采用EN技术实现对缓蚀剂保护效果的原位无损监测。     

竹叶提取液的制备及其缓蚀性能

植物提取液低毒,低残留,易后处理,用作缓蚀剂时环保性好.为此,用15%H_2SO_4浸泡竹叶,以其提取液配制成缓蚀剂.采用电化学测试、失重和腐蚀浸泡试验研究了竹叶不同浸泡时间、竹叶提取液浓度对Q235钢缓蚀性能的影响.结果表明:将适量竹叶用15%的硫酸浸泡306 min配制成的0.1 g/mL溶液,缓蚀效率达96%以上,是一种阳极型缓蚀剂;电化学研究表明,竹叶提取液为混合型缓蚀剂,作用机理为几何覆盖效应;失重结果表明,竹叶提取液的缓蚀效率随其浓度的增加而增大,在硫酸介质中在Q235碳钢表面的吸附符合El-Awady动力学模型与Flory-Huggins吸附等温方程.     

氮掺杂碳点对Q235钢的缓蚀性能及机理研究

以聚乙烯吡咯烷酮为原料,采用水热法合成了一种环保、高效的氮掺杂碳点(N-CDs)。利用傅里叶变换红外光谱(FTIR)对其结构进行了表征,采用电化学方法、失重法和扫描电子显微镜(SEM)研究了N-CDs在1 mol/L HCl溶液中对Q235钢的缓蚀性能和缓蚀机理。结果表明,当N-CDs的用量为200 mg/L时,缓蚀率可高达95.6%。电化学试验表明,N-CDs是一种混合型缓蚀剂,但主要是抑制阳极的反应。其缓蚀机理是:N-CDs在Q235钢表面以物理吸附和化学吸附的共同作用在Q235钢表面形成稳定的吸附膜,从而有效地抑制1 mol/L HCl溶液对碳钢的腐蚀,且符合Langmuir等温吸附模型。另外,SEM清晰观察到加入N-CDs后,Q235钢的腐蚀程度得到了明显的改善。     

马齿苋提取液对盐酸溶液中Q235碳钢的缓蚀作用

为了开发新型环境友好的天然缓蚀剂,采用索氏提取法提取马齿苋中的有效成分,采用失重法、动电位极化曲线和交流阻抗研究了不同浓度马齿苋提取液在1.0 mol/L盐酸溶液中对Q235碳钢的缓蚀作用及机理。结果表明:马齿苋提取液在盐酸介质中对碳钢具有良好的缓蚀效果,缓蚀效率随缓蚀剂浓度增大而升高,30℃下当提取液的浓度达到0.16 g/m L时,其缓蚀效率可达91%以上;随温度升高,马齿苋提取液对碳钢的缓蚀效率降低;马齿苋提取液是一种抑制阴阳极反应的混合型缓蚀剂,有效成分吸附在碳钢表面形成一层保护膜,吸附过程遵循Langmuir等温方程式,其在碳钢表面的吸附属于自发过程,是以化学吸附为主的物理和化学吸附共同作用的过程。     

氨基磺酸中肉桂醛缩甲胺席夫碱对Q235钢的缓蚀吸附行为

为进一步研究肉桂醛缩甲胺席夫碱在氨基磺酸介质中对碳钢的腐蚀机理,利用极化曲线、原子力显微镜、X射线光电子能谱仪和量子化学计算,研究了5%氨基磺酸介质中肉桂醛缩甲胺席夫碱在Q235钢表面的缓蚀吸附行为。结果表明:在70℃、5%氨基磺酸介质中,肉桂醛缩甲胺在Q235钢表面的吸附行为符合Langmuir吸附等温式,是一种混合型缓蚀剂,且该缓蚀剂在Q235钢表面的吸附存在不均匀性;Q235钢在氨基磺酸溶液中的腐蚀产物主要为Fe SO4、Fe S,缓蚀剂的吸附抑制了Fe S的生成。     

鲜白酒糟提取液对Q235钢硫酸酸洗的缓蚀性能

为了综合利用白酒糟和开发新型绿色酸洗缓蚀剂,制取了鲜白酒糟提取液,采用失重法和电化学法研究了其作为硫酸酸洗缓蚀剂的缓蚀性能。结果表明:15 g酒糟在300 mL 5%硫酸溶液中30℃静置浸泡6 h,得到的提取液在5%硫酸介质中对Q235钢的缓蚀率最高;酒糟提取液在Q235钢表面的吸附符合El-Awady动力学模型和Flory-Huggins吸附等温方程,属于几何覆盖效应的单分子层吸附,提取液为混合型缓蚀剂;放置时间延长时,提取液的缓蚀率降低。     

Q235碳钢在不同浓度和温度的十二硫醇中的腐蚀行为

目前,研究金属材料在十二硫醇中腐蚀行为的报道较少。将Q235碳钢挂片于不同浓度和温度的十二硫醇中进行腐蚀,并计算腐蚀速率;采用扫描电镜(SEM)、X射线衍射仪(XRD)和X射线光电子能谱仪(XPS)对Q235碳钢表面腐蚀形貌和成分进行了观察和分析,并研究了腐蚀机制。结果表明:Q235碳钢在十二硫醇中的腐蚀速率和腐蚀机制与十二硫醇在Q235碳钢表面的吸附和覆盖状况密切相关,当十二硫醇的浓度从低到高变化时,其在Q235碳钢表面的吸附量和覆盖度也表现出从低到高的特征,Q235碳钢从局部腐蚀转变为均匀腐蚀;Q235碳钢在十二硫醇中的腐蚀速率随着温度的升高而逐渐增大,且两者之间基本满足线性关系;Q235碳钢表面腐蚀产物呈多裂纹的疏松结构,主要物相成分为Fe_2O_3、Fe_3O_4、FeS和FeS_2。     

壳聚糖季铵盐在HCl溶液中对Q235钢的缓蚀性能

目前,关于壳聚糖类缓蚀剂的报道较少,且研究温度窄,鲜见对其吸附动力学参数的分析。合成了羟丙基三甲基氯化铵壳聚糖(HACC),在30~60℃温度范围内,通过浸泡失重、电化学分析、形貌观察等方法研究了其在0.5 mol/L HCl溶液中对Q235钢的缓蚀效果。结果表明:缓蚀效率随HACC浓度升高而增加,随温度升高而降低,在30℃、HACC浓度为1.5 mmol/L时,缓蚀效率最高;HACC同时抑制了Q235钢腐蚀的阴阳极过程,通过抑制反应的活性点而起缓蚀作用;HACC在Q235钢表面的吸附符合Langmuir等温吸附模型,是自发的放热过程,属于物理和化学混合吸附,活化能是Q235钢腐蚀速率的决定性因素。     

典型接地材料在陕北黄土高原土壤模拟液中的短期腐蚀行为

目前,有关陕北黄土高原土壤对典型接地材料的腐蚀研究鲜有报道。采用浸泡试验、EIS测试和表面分析方法,研究了Q235碳钢、镀锌钢、镀铜钢、紫铜和304不锈钢在陕北黄土高原土壤模拟液中的腐蚀行为。结果表明:5种典型接地材料在其土壤模拟液中的耐蚀性大小顺序为304不锈钢紫铜镀铜钢镀锌钢Q235碳钢;Q235碳钢的腐蚀产物具有明显的层状结构,腐蚀产物内层紧密,对基体有较好的保护作用,外层疏松,氧化充分;镀锌钢、镀铜钢和紫铜的表面腐蚀产物分别主要为锌和铜的氧化物;304不锈钢的表面未见明显的腐蚀产物。     

温度对新型咪唑啉抑制CO2腐蚀的影响

关于温度对油田环境中咪唑啉缓蚀性能影响的研究较少。自制了硫脲基咪唑啉,研究对比了其在358K和298K下对CO2的缓蚀性能。采用失重法测定了该咪唑啉缓蚀剂在358K下对Q235-A钢在饱和CO2盐溶液中的缓蚀率;利用动电位极化曲线、交流阻抗法研究了Q235-A钢在饱和CO2盐溶液中温度对该缓蚀剂缓蚀行为的影响,探讨了吸附膜的形成与衰减规律。结果表明:该缓蚀剂对Q235-A钢的缓蚀作用具有浓度极值,极值浓度为40mg/L;2种温度下,该缓蚀剂都属于抑制阳极过程为主的混合型缓蚀剂,成膜速度较快,24h即可形成致密的吸附膜;低温条件下比高温时成膜更加紧实致密、稳定性好,膜寿命长。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。