Effect of Zr addition on the interfacial reaction of the SiC joint brazed by Inconel 625 powder filler

Ni-based alloys are believed to be the most suitable brazing fillers for SiC ceramic application in a nuclear environment. However, graphite, which severely deteriorates the mechanical property of the joint, is inevitable when Ni reacts with SiC. In this paper, Different amounts of Zr powders are mixed with Inconel 625 powders to braze SiC at 1400 °C. When Zr addition reaches 40 wt%, the brazed seam confirms the absence of graphite. This research proves that Zr can avoid the graphite’s formation by suppressing Ni’s activity. The room-temperature shear strength of the joint with graphite’s absence is tested to be 81.97 MPa, which is almost three times higher than that of the joint with graphite. The interfacial reaction process and mechanism of the SiC joint are investigated and explained in this paper using thermodynamic calculations.     

氟塑料—石墨板式换热器在高温强腐蚀换热工况中的应用

通过氟塑料－石墨板式换热器在化纤生产中高温强腐蚀换热工况中的实际应用，并与常规换热器的使用情况的对比分析，阐述了这种新型换热设备的特点。     

Microwave-Assisted Graphite-Support Synthesis of Imidazolones

5(4H)-Oxazolones react with ammonium acetate under microwave irradiation and using graphite as support in an eco-friendly process. The reaction was carried out under solvent-free conditions and the imidazolones were obtained quantitatively. Moreover the reaction time was reduced too.     

Complementary effects of solid lubricants in the automotive brake lining

An experimental investigation was carried out to examine the tribological behavior of NAO (non-asbestos organic) type brake linings containing different volume ratios of graphite and antimony trisulfide (Sb₂S₃). A scale dynamometer was used for friction tests and particular emphases were given to the effect of applied pressure, sliding speed, and temperature on the coefficient of friction according to the relative amounts of the two solid lubricants. Results showed that the brake linings with both solid lubricants exhibited better friction stability and less speed sensitivity than the friction materials containing a single solid lubricant. In particular, the brake lining containing higher concentrations of graphite showed better fade resistance than others during high-temperature friction test.     

Graphite formation on Ni film by chemical vapor deposition

Thin film formation of graphite by chemical vapor deposition using 2-methyl-1,2′-naphthyl ketone as a starting material was carried out on Ni film substrates. On Ni films directly deposited on quartz glass, the graphite films were obtained when the Ni film thickness was above 1 000 Å and above 5 000 Å at 700 °C and 1 000 °C, respectively. Depositions on thinner Ni film substrates comprise amorphous carbon (a-C) or graphite tubes which was owing to the thermal coagulation of the Ni film into droplets. On the other hand, graphite film was obtained on the Ni film with thickness 10 Å when a-C was inserted between the Ni film and the quartz glass. The coagulation of the Ni film is considered to be avoided by inserting a-C layer.     

Durability of hygrothermally aged graphite/epoxy woven composite under combined hygrothermal conditions

The objective of this study was to examine the effects of hygrothermal aging on the durability of a graphite/epoxy woven composite material system. The study was part of a larger project in which the objective was to evaluate and model the effects of moisture, temperature, and combined hygrothermal conditions on the strength and life of a graphite/epoxy woven composite material system. The results presented here represent an extension of the work by Patel and Case (Int. J. Fatigue 22 (2000) 809).

The hygrothermal aging consisted of cyclical temperature and moisture variations which were meant to simulate mission conditions for an advanced subsonic aircraft. Durability studies were carried out on the aged material system in the form of fatigue and residual strength testing under humid and elevated temperature environments. Damage mechanisms and failure modes were determined through fatigue testing, residual strength testing, and nondestructive evaluation.

Changes in physical appearance, thermal analysis results, fracture surfaces, and moisture diffusion behavior all supported the idea that the material was affected by the aging process. However, experimental testing also showed that the initial and residual tensile properties of the aged material were virtually unaffected by the imposed environmental aging (as compared to unaged material testing results), except when tested at elevated temperature. At elevated temperature, both the dynamic stiffness and residual strength were noticeably reduced from that at room temperature.     

Synthesis and properties of polystyrene/graphite nanocomposites

In this paper, graphite/polystyrene nanocomposite is synthesized by in situ polymerization of styrene in a tetrahydrofuran (THF) solution system of potassium (K)-THF-graphite intercalation compound (GIC). K-THF-GIC has proved to initiate polymerization of styrene by the anionic mechanism. Due to the interfacial interaction between the graphite nanolayers and the polymer, the composites exhibit higher glass transition temperature and higher thermal stability when compared to polystyrene. The percolation threshold in the conductivity of the composites is lesser than 8.2 wt% and the dielectric constant can reach as high as 136.     

固体润滑涂层的评价和使用

本文主要介绍了二硫化钼，石墨、聚四氟乙烯三种固体润滑涂层的特点以及润滑涂层摩擦磨损性能的评价手段和方法，以及台架试验和应用实例，提出了选用方法和步骤。     

Influence of pencil lead hardness on voltammetric response of graphite reinforcement carbon electrodes

This work studied the voltammetric response of graphite reinforcement electrodes made of different pencil lead hardness. The studies showed that harder graphite leads, regardless of their manufacturer, are more appropriate as electrode material for voltammetric purposes due to their higher peak currents, increasing sensitivity and reproducibility, with ΔEp closer to the theoretical value for a reversible system.     

Dissociative adsorption of small molecules at vacancies on the graphite (0 0 0 1) surface

The adsorption of molecular and atomic hydrogen as well as other molecules in the atmosphere on vacancies in the (0 0 0 1) graphite surface are investigated using density functional theory. Atomic hydrogen adsorbs with energies ranging from 4.7 to 2.3 eV. The validity of the model is confirmed by the good agreement between calculated vibrational spectra and those of high-resolution electron energy loss spectroscopy. It is shown that molecular hydrogen dissociates with a barrier of 1.1 eV on this model system. Water and oxygen also dissociate with respective barriers of 1.6 and 0.2 eV. Carbon dioxide and nitrogen have no interaction with the defect whereas carbon monoxide is incorporated into the vacancy with an activation energy of 1.5 eV. A comparison is made with the reactivity of graphene edges, both zigzag and armchair.