The oil solubility of synthetic oleic acid tris-(2-hydroxyethyl) isocyanurate phosphate ester(abbreviated as OHTP hereinafter) and its influence on the biodegradability and tribological performance of 400 SN mineral oil were investigated on a tester and a four-ball tribotester,respectively,for fast evaluating the biodegradability of lubricants.Furthermore,the morphologies and tribochemical species of the worn surfaces lubricated by OHTP-doped oil were studied by scanning electron microscope(SEM) and X-ray photoelectron spectroscope(XPS).The results indicated that OHTP possessed good oil solubility and could improve obviously the biodegradability,the extreme pressure properties,the anti-wear properties and friction-reducing properties of the 400 SN mineral oil.The analytical results of XPS spectra showed that the composite boundary lubrication films were mainly composed of absorbed films and tribochemical species such as FePO-4,Fe_3(PO_4)_2,Fe_2O_3 and Fe_3O_4,which contributed to improving the tribological performances.
Different contents of biodiesel and petrodiesel were incorporated into diesel engine oils. The oxidative stability, detergency and antiwear performance of the formulated diesel oils were evaluated. The results indicated that, compared with petrodiesel, biodiesel was more liable to promote oxidation degradation of diesel oils, leading to worse oxidative stability, detergency and antiwear ability of the oils.
The influence of synthetic caprylic methyl diethanolamine phosphate ester (abbreviated as MDEACP) on biodegradability and tribological properties of 400SN mineral base oil was studied. The biodegradability of the neat base oil and the oil doped with MDEACP was determined on a biodegradation tester. The tribological properties of the neat base oil and the oil doped with MDEACP were evaluated on a four-ball tester. Moreover, the worn surfaces were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results revealed that MDEACP significantly promoted the biodegradation of the mineral base oil. The improvement in biodegradability was attributed to the enhanced growth and quantity of microbes by MDEACP. Furthermore, MDEACP enhanced the anti-wear properties, the friction-reducing properties, and the extreme pressure properties of the base oil. It was mainly attributed to the formation of the complex boundary lubrication film resulted from the adsorption and tribochemical reactions of MDEACP on the friction surface.
Ding JianhuaFang JianhuaChen BoshuiLiu PingFan XingyuChen Ran
Assessment of human airway humen opening is important in diagnosing and understanding the mechanisms of airway dysfunctions such as the excessive airway narrowing in asthma and chronic obstructive pulmonary disease(COPD).Although there are indirect methods to evaluate the airway calibre,direct in vivo measurement of the airway calibre has not been commonly available.With recent advent of the flexible fiber optical nasopharyngoscope with video recording it has become possible to directly visualize the passages of upper and lower airways.However,quan-titative analysis of the recorded video images has been technically challenging.Here,we describe an automatic image processing and analysis method that allows for batch analysis of the images recorded during the endoscopic procedure,thus facilitates image-based quantification of the airway opening.Video images of the airway lumen of volunteer subject were acquired using a fiber optical nasopharyngoscope,and subsequently processed using Gaussian smoothing filter,threshold segment ation,differentiation,and Canny image edge detection,respectively.Thus the area of the open airway lumen was identified and computed using.a predetermined converter of the image scale to true dimension of the imaged object.With this method we measured the opening/narrowing of the glottis during tidal breathing with or without making“Hee"sound or cough.We also used this met hod to measure the opening/narrowing of the primary bronchus of either healthy or asthmatic subjects in response to hist amine and/or albuterol treatment,which also provided an indicator of the airway contractility.Our results demonstrate that the image-based method accurately quantifed the area change waveform of either the glottis or the bronchus as observed by using the optical nasopharygoscope.Importantly,the opening/nar-rowing of the airway lumen generally correlated with the airAow and resistance of the airways,and could differentiate the level of airway contr actility between the healthy and asthmatic subjects.Thus,t
Tribological properties of neat 150 SN mineral base oil and the oils doped with different contents of tricresyl phosphate(TCP) under magnetic field or non-magnetic field were evaluated on a four-ball tribotester, on which an external magnetic field was applied. Furthermore, the morphology and the tribochemical characteristics of the worn surfaces were examined with a scanning electron microscope(SEM) and an X-ray photoelectron spectrograph(XPS). The tribological test results showed that the magnetic field improved anti-wear properties but impaired the friction-reducing properties of neat base oil and the TCP-doped oils. The worn surfaces tested in magnetic field were characterized by a slighter wear than those tested in normal condition, especially for the surfaces lubricated with the TCP-doped oils. Furthermore, the results of XPS analysis indicated that tribochemical films on the surfaces tested with TCP-doped oils were mainly composed of ferriccontaining compounds such as Fe_2O_3, Fe_3O_4 and FePO_4. Under the influence of a magnetic field, the atomic concentrations of oxygen and phosphorous in the frictional sub-surfaces were higher than those without magnetic impact. Thus it can be inferred that the improved anti-wear properties and impaired friction-reducing capabilities of lubricating oils with TCP under a magnetic field were related to the diffusion of phosphorus and oxygen into the substrate induced by magnetism.
Jiang ZeqiFang JianhuaChen BoshuiZheng ZheLi HaoXu Lai
The thermal decomposition characteristics of methyl linoleate （ML） under nitrogen and oxygen atmo- spheres were investigated, using a thermogravimetric analyzer at a heating rate of 10 ~C/min from room tem- perature to 600℃. Furthermore, the pyrolytic and kinetic characteristics of ML at different heating rates were stud- ied. The results showed that the thermal decomposition characteristics of ML under nitrogen and oxygen atmo- spheres were macroscopically similar, although ML exhibited relatively lower thermal stability under an oxy- gen atmosphere than under a nitrogen atmosphere. The initial decomposition temperature, the maximum weight loss temperature, the peak decomposition temperature, and the rate of maximum weight loss of ML under an oxygen atmosphere were much lower than those under a nitrogen atmosphere and increased with increasing heating rates under either oxygen or nitrogen atmosphere. In addition, the kinetic characteristics of thermal decomposition of ML were elucidated based on the experimental results and by the multiple linear regression method. The activation energy, pre-exponential factor, reaction order, and the kinetic equation for thermal decomposition of ML were obtained. The comparison of experimental and calculated data and the analysis of statistical errors of pyrolysis ratios demonstrated that the kinetic model was reliable for pyrolysis of ML with relative errors of about 1%. Finally, the kinetic compensation effect between the pre-exponential factors and the activation energy in the pyrolysis of ML was also confirmed.
Tribological properties of 150 SN mineral oil and the oils doped with different contents of zinc butyloctyldithiophosphate(T202) under magnetic field or non-magnetic field were evaluated on a four-ball tribotester by applying an external magnetic field around the friction region. Moreover, the morphology and the tribochemical characteristics of worn surfaces were examined by a scanning electron microscope(SEM) and an X-ray photoelectron spectrometer(XPS). Then the lubrication mechanisms were discussed. The tribological test results indicated that the wear scar diameters(WSDs) of steel balls lubricated by the T202-containing lubricating oils and the friction coefficients of the corresponding oil under magnetic field were smaller than those without magnetic affection. The worn surface lubricated with the T202-formulated oils in a magnetic field was smoother than that obtained under the normal condition. Furthermore, the results of XPS analysis indicated that tribochemical films on the surfaces lubricated with T202-doped oils were mainly composed of compounds such as FeSO_4, FeS and ZnS. The atomic concentrations of oxygen, sulfur, iron, zinc and phosphorus species identified in T202 under magnetic field were higher than those without magnetic impact. It can be inferred that the improved anti-wear and friction-reducing ability of T202-doped oils was attributed to the promoted tribochemical reactions and the modification of the worn surfaces induced by magnetic field.
Considering electromagnetic effect when investigating tribological properties of rapeseed oil is benefical not only to the improvement of green lubrication, but also to the development of tribology theories and practices. In the present paper, the tribological properties of rapeseed oil under different intensity of electromagnetic field and normal loads were evaluated on a modified tribo-tester. The results indicated that the electromagnetic field could improve the anti-wear and friction-reducing property of the rapeseed oil. Furthermore, the influencing mechanisms were discussed from the perspective of electromagnetism according to the analytical results of SEM, EDS and XPS techniques.
