摩擦化学反应对发动机油润滑耐久性能的影响

利用SRV高温摩擦磨损试验机比较了两种分别属于GF-2和GF-3等级，含有MoDTC摩擦改进剂的发动机油的耐久性。结果表明，由于GF-3等级发动机油能使活塞环和缸套试样表面更加平整光滑，且由于Ca清静剂与MoDTC／ZDTP的协同作用，通过摩擦化学反应，在摩擦表面形成良好的摩擦反应膜，从而使它拥有更好的润滑耐久性能。     

Micromechanical machining of soda lime glass

Micromechanical machining, which is the mechanical removal of materials using miniature cutting tools, is one of the fabrication methods in the microrealm that has recently attracted a great deal of attention because it has the advantage of being able to machine complex shapes from brittle materials. The most challenging problem in the mechanical machining of brittle material is the fabrication of fracture-free surfaces. To avoid brittle fractures, a thorough investigation is required to find the machining parameters in the ductile cutting regime, which is characterized by plastic deformation of the material when the chip thickness is smaller than the critical value. In this study, cutting forces and surface characteristics of soda lime glass are examined in detail. Conical scratch tests are performed to identify the critical chip thickness, and the cutting forces in the ductile regime are modeled. In addition, coated ball end mill cutters were used to perform machining on inclined soda lime glass to investigate the feed rate effects, up and down milling, and depth of cuts on the surface finish and to examine tool wear.     

Micromechanical scribing and indentation behavior of injection-molded polymeric carbon nanotube (CNT) nanocomposites

Polymeric carbon nanotube (CNT) nanocomposites have unique mechanical, electrical, and thermal properties. Anisotropy can be induced depending on the alignment of the CNT fillers within polymeric composites, which is known to affect material properties. In order to investigate the effects of CNT alignments in micromechanical scribing using a single crystal diamond tool, a microindenter–scriber system was developed. Multiwalled carbon nanotube–polystyrene (MWCNT–PS) samples with varying CNT concentrations were prepared through a microinjection molding process, where the injection enables the partial alignment of CNTs in the flow direction through high shear stress. A mechanistic scribing force model was proposed based on the material properties that could be obtained using the microindentation techniques. Scribing experiments were performed in the parallel and perpendicular directions to the CNT alignment. Forces in three axes were measured and analyzed to identify three unknown parameters—the shearing, plowing, and adhesion friction coefficients. The resulting coefficients for scribing perpendicular to the CNT alignment showed distinguishable trends from scribing parallel to the CNT alignment as the CNT loadings increased. Their linear trends in relation to the material properties identified from indentation techniques can be used to predict microscribing parameters and resulting cutting forces, in combination with the proposed mechanistic model.     

Tribological Investigation of the Polymer-Based Lubrication System Using a Laboratory Reciprocating Bench Test

Flooded oil lubrication systems are commonly utilized for many manufacturing processes. However, there is an increasing concern with the flooded lubrication systems due to their biological and environmental impact as well as their maintenance and disposal cost. Polymer-based material, a sponge-like solid lubricant allowing the oil to weep out while in use, provides a promising alternative environmentally benign lubrication solution to satisfy the lubrication requirements for some manufacturing processes. In addition, it can minimize contamination of the coolant system, reduce waste processing and disposal costs, and alleviate the in-plant safety hazard from oil leakage on floor surfaces.

The goal of this study is to develop and improve the current lubrication system by applying a polymer-based near-dry lubrication system in order to replace the oil-flooded transfer line lubrication systems currently in production use. Using a laboratory reciprocating bench test based on the design of experiments, this study characterized the tribological performance of the polymer-based lubrication system under a variety of operating conditions, identified the main factor that impacts the tribological performance of the polymer-based lubrication system, and developed a model to predict the wear loss of the polymer-based lubricant plate. These results provide the guidelines for possible applications of the polymer-based lubrication system used in the manufacturing process.     

Microscopic Contour Changes of Tribological Surfaces by Chemical and Mechanical Action

An electronic optical laser interferometer capable of resolving depth differences of as low as 30 Å and planar displacements of 6000 Å was constructed for the examination of surface profiles of bearing surfaces without physical contact. This instrument was used to determine topological chemical reactivity by applying a drop of dilute alcoholic hydrochloric acid and measuring the profile of the solid surface before and after application of this probe. It was found that scuffed bearing surfaces exposed to lubricants containing an organic chloride reacted much more slowly. In a separate series of experiments, a number of stainless steel plates were heated in a nitrogen atmosphere to different temperatures and their reactivity examined later at ambient temperature. The change of surface contour as a result of the probe reaction was found to follow an Arrhenius-type relation with respect to heat treatment temperature. This result could have implications on the scuffing mechanism.     

Thermochemical Treatment--Technologies for Recovery and Utilisation of Materials

The arc furnace technology is an ideally suited process for the treatment of hazardous and problematic waste. The operation conditions of the arc furnace can be adapted for optimal transformation of the waste material input into raw materials and usable products. The process can significantly reduce the impact of contaminated wastes and industrial residues, and enable material conversion and separation. Thus, the products of the process have various applications. The capability of the process is illustrated with three examples, the treatment of bottom ash and filter ash from waste incineration plants, of stainless steel slags and of chromium containing residues from the refractory industry.     

Anion binding involving pi-acidic heteroaromatic rings

Anions are essential species in biological systems and, particularly, in enzyme-substrate recognition. Therefore, the design and preparation of anion receptors is a topical field of supramolecular chemistry. Most host-guest systems successfully developed are based on noncovalent (ionic and hydrogen-bonded) interactions between anions and ammonium-type functionalities or Lewis acid groups. However, since the past 5 years, an alternative route toward the synthesis of efficient anion hosts has emerged, namely, the use of "anion-pi" interactions involving nitrogen-containing electron-deficient aromatic rings, as the result of several favorable theoretical investigations. In this Account, the state of the (new) art in this growing area of anion-binding research is presented and several selected examples from our work and that of other groups will be discussed.     

Effects of ring substituents on the protective properties of self-assembled benzenethiols on copper

The self-assembled monolayers (SAMs) of a series of substituted benzenethiol (BT) molecules, X-C₆H₄-SH (where X = meta-NH₂, ortho-NH₂, para-NH₂, para-NHCOCH₃, para-F, para-CH₃ and para-CH(CH₃)₂), have been prepared by adsorption from a solution onto a fresh copper (Cu) surface pretreated by a nitric acid etch. The corrosion inhibition efficiency of the modified Cu surfaces in a sulfuric acid solution was investigated by electrochemical characterization. The protection afforded by the substituted functional groups on BT is strongly influenced by the type and the position of the substituent on the benzene ring. BT molecules without any substituent group on the ring are ineffective corrosion inhibitors, indicating that the chemical configuration is the key factor in determining the efficacy of the SAMs as barriers to electrochemically corrosive ions. It is further proposed that the steric hindrance offered by the substituted group in the SAMs plays a very important role in determining its barrier properties.     

Polyimides with 3,3’-Bipyrrolidine-2,2’,5,5’-Tetrone Units

Summary New linear polymers with 3,3’-bipyrrolidine-2,2’,5,5’-tetrone units were prepared by the ring-coupling reaction of α,α’-bis(chlorosuccinimide)s under the action of dust zinc and iodine. Bis(α-chlorosuccinimide)s were synthesized by the dehydrocyclization of the bismaleamic acids in the presence of thionyl chloride. The IR, ¹H-NMR and ¹³C-NMR spectroscopy and elemental analysis confirmed the structure of monomers and polymers. The thermal behaviour of the polymers was monitored using dynamic thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).