烟叶油润度参比样的制作与分析

为方便烟叶评级人员准确把握烟叶油润度概念,从烟叶评级实践的角度出发以及根据国家标准(GB2635-1992)《烤烟》中油分的定义,采取感官分析方法,遵循参比样的制作原则,制作了7个档次的烟叶油润度实物参比样品,进行特征描述、档次排序。统计分析结果表明:各参比样样品评价排序数据具有很强的一致性,档次之间存在极显著差异,此套参比样品符合重复性和再现性,适用性较强。

烤烟油润度感官因子参比样的制作与分析

采取感官分析的方法,对油润度参比样采用Friedman检验等多种检验方法将油润度划分为5个标度,并建立相应的描述词。同时对各标度参比样物理指标、化学指标及感官评价进行了检测。结果表明:上述指标与烟叶油润度密切相关,且不同标度参比样品在上述指标间有明显的梯度和差距。

青海软玉中硅灰石的确定及其意义

经镜下观察和X射线粉晶衍射分析发现,青海软玉中普遍含有硅灰石,这与新疆软玉形成了鲜明的对比。硅灰石的存在增加了青海软玉的透明度,降低了油润度,对青海软玉的质量产生较大的影响。

Rapidly determining kinematic viscosity of aviation lubricating oil 50-1-4Φ by mid-infrared spectrometry

This paper analyzed 11 lubricating oil 50-1-4Ф samples of different base oil content （standard oil） and 28 used oil samples by Fourier transform mid-infrared spectrometer （FTIR）. First, the absorption peak of 1 465 cm 1 was selected as the characteristic peak for determining their kinematic viscosities. And then correlation of the kinematic viscosity and the absorbance at characteristic peaks of corresponding infrared spectrum of standard oil and used oil samples was analyzed, re- spectively, and two regression equations were proposed. Finally, the regression equation of standard oil was corrected through other 20 new oil samples. The results show that determining kinematic viscosity of new lubricating oil 50-1-4Ф and the used one by FTIR is feasible and reliable.

The Influence of Paraffinic Base Oil on Low-temperature Viscosity of Naphthenic Base Oil

Low-temperature viscosity of lube oils mixed with paraffinic base oil and naphthenic base oil at different mass ratios has been tested by experiments. The influence of paraffinic base oil on the performance of naphthenic base oil was investigated by studying the low-temperature viscosity of tested oils. The viscosity of lube oils increased with an increasing content of high-viscosity paraffinic base oil in the oil mixture. And the low-temperature viscosity was less influenced when the content of paraffinic base oil in the mixture was insignificant. In order to reduce the cost for formulating lubricating oil, a small fraction of paraffinic base oil can be added into naphthenic base oil as far as the property of lubricating oil can meet the specification. According to the study on low-temperature viscosity of the oil mixed with paraffinic base oil and naphthenic base oil, a basic rule was worked out for the preparation of qualified lubricating oils.

A Generalized Correlation for Characterization of Lubricating Base-oils from Their Viscosities

Lubricating mineral base oils are normally extracted from lube-oil cuts with furfural solvent.Aromatic content in the raffinate phase from extraction process is an essential parameter that affects the quality of the lubricating base-oils.For determination of aromatic content by the usual ASTM D3238 method,density,refractive index and molecular weight of the raffinate are required.In this work,a new generalized correlation is developed for de-termination the aromatic content by using only the measured viscosity of lubricating oil.With a mole fraction of aromatic compounds,the kinematic viscosity may be obtained at any temperature between 60-100°C along with their molecular weight and refractive index.

Analysis of lubrication performance for internal meshing gear pair considering vibration

The thermal elasto-hydrodynamic lubrication characteristics of the internal meshing gears in a planetary gear train under vibrations were examined considering the influence of the modification coefficient and time-varying meshing stiffness.Based on dynamic theory of the gear system,a dynamic model of the planetary gear train was established.The lubrication performances of modified gear systems under vibrations and static loads were analyzed.Compared with other transmission types,the best lubrication effect could be produced by the positive transmission.A thicker lubricating oil film could be formed,and the friction coefficient and oil film flash temperature are the smallest.Increasing modification coefficient improves the lubrication performance continuously but intensifies the engage-in and tooth-change impact.For the planetary and inner gears,the increase in the modification coefficient also leads a decrease in the oil film stiffness.

Performance evaluation of minimum quantity lubrication by vege-table oil in terms of cutting force,cutting zone temperature,tool wear,job dimension and surface finish in turning AISI-1060 steel

In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (MQL) has been suggested since a decade ago as a means of addressing the issues of environmental intru- siveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.

Thermal elastohydrodynamic lubrication of modified gear system considering vibration

The thermal elastohydrodynamic lubrication characteristics of a modified gear system under a dynamic load were investigated,including the influence of the modification coefficient and vibrations.Based on the dynamic theory of gear systems,a six-degree-of-freedom tribo-dynamics model was established.Thermal elastohydrodynamic lubrication characteristics of a modified gear system under vibrations and a static load were analyzed.The results showed that the positive transmission gear system exhibited the better lubrication effect compared with other transmission types.A thick lubricating oil film could be formed,and the friction coefficient between the teeth and the oil film flash temperature were the smallest.As the modification coefficient increased,the lubrication condition was continuously improved,and the scuffing load capacity was enhanced.The increment of the modification coefficient increased the meshing stiffness of the gear system but reduced the stiffness of the oil film.

Effects of Fatty Acids on Low-Sulfur Diesel Lubricity:Experimental Investigation, DFT Calculation and MD Simulation

The continuous reduction in sulfur content of fuels would lead to diesel fuel with poor lubricity which could re- sult in engine pump failure. In the present work, fatty acids were adopted as lubricity additives to low-sulfur diesel fuel. It was attempted to correlate the molecular structures of fatty acids, such as carbon chain length, degree of saturation and hy- droxylation, to their lubricity enhancement, which was evaluated by the High-Frequency Reciprocating Rig （HFRR） meth- od. The efficiency order was supported by the density functional theory （DFT） calculations and the molecular dynamics （MD） simulations. The lubricity enhancing properties of fatty acids are mainly determined by the cohesive energy of adsorbed films furmed on iron surface. The greater the cohesive energy, the more efficiently the fatty acid would enhance the lubricity of low-sulfur diesel fuel.

Friction Characteristics of Space Lubricating Oil No.4129 in Rolling and Sliding Contact

The friction coefficients between the surfaces of a ball and a disc lubricated by a space lubricating oil No.4129 were measured at various operating conditions on a ball-disc friction test rig. Friction characteristic curves were obtained under sliding and rolling movements at point contact. A new model for calculation of the friction coefficient was presented. The results show that the bigger the load is, the larger the friction coefficient becomes. The rolling speed ranging from 1 m/s to10 m/s has an important effect on the friction coefficient. The friction coefficient increases with the increase in sliding speed and the decrease in rolling speed. The linear variation region of the friction coefficient versus the sliding speed at high rolling speed is wider than that at low rolling speed. The model for calculation of the friction coefficient is accurate for engineering use.

Lubricating properties of oil-in-water emulsion with low oil concentration:Competitive wetting effect

Oil-in-water （O/W） emulsions are widely used in metal working such as hot rolling and cutting. Three kinds of O/W emulsions with low oil concentration were prepared which include conventional emulsion （CE）, miniemulsion （MNE） and microemulsion （ME）. The lubricating properties of O/W emulsions with low oil concentration were investigated using the tribological testers and the thin film interferometry based on the relative optical interference intensity method. The tribological test results under boundary lubrication show that the friction coefficient and the total losing weight can be clearly seen： CE 〈 MNE 〈 ME. The lubricating film thicknesses under elastohydrodynarnic lubrication and thin film lubrication show that a relationship of the film formation abilities： CE 〉 MNE 〉 ME. Competitive wetting behavior of water and oil on solid surface was confirmed to play an important role in the film formation and tribological behaviors of O/W emulsion.

Experimental research on reasonable lubricant quantity for transmission gears used in high-speed train

The transmission efficiency, bulk temperature, integrate temperature, and scuffing load of test gears were investigated by a modified FZG rig. These values were measured in four different oil immersion depths with one kind of potential oil that may be used to replace the current synthetic oil in order to find the reasonable lubricant quantity that meets not only the need of transmission performance but also the need of scuffing resistance for high-speed train gears. For the purpose of evaluating the efficiency of the test gears, there were two sensors added to measure the output torque of testing gears and the compensation torque of motor. The minimum lubrication film thickness at the pitch point was gained through an EHL model. The ratio of the film thickness A was used to identify the friction status when scuffing occurred at different oil levels. The results demonstrated that no matter what kind of the immersion depth was, the minimum film thickness on the pitch point was about 0.1 ~m and the ratio of film thickness was about 1.5 when scuffing occurred. According to the relationship of contact pressure and ratio of film thickness at the pitch point, it was found that the immersion depth of pinion should not be less than one module of the gear when the contact pressure of high-speed train gear at pitch point was about 580 MPa, which was the actual pressure at start-up stage.