Graphite Steel Research Articles

Sliding Layer Formation during Tribological Contact between Expanded Graphite and Stainless Steel—A Pilot Study

The sliding layer created during operation of the expanded graphite–steel combination has had a huge impact on the effectiveness of the friction process, and thus on the sustainable development of society. Knowledge of the factors determining the properties of the sliding layer will make it possible to reduce friction resistance in the future through the proper design and selection of sliding pairs for given applications. This paper studies the effect of the moisture content of expanded graphite on the formation of a sliding layer on a stainless steel surface. The tests were carried out in static contact for 30 s and dynamic contact for 15 and 30 min, for loads of 10, 20, and 30 N and speeds of 25 and 50 mm/s. To determine the changes in surface geometry due to material transfer, the Ra roughness value of the surface of stainless steel samples was measured. In order to realize the purpose of the work and evaluate the effect of moist rings on the resulting sliding layer, the results of the surface roughness of stainless steel samples working with dry and moist graphite rings were compiled. The obtained results show that the presence of water in the stainless steel-expanded graphite friction node affects the formation of a sliding layer. The resulting layer reduces the surface roughness of the cooperating materials and prevents their accelerated wear. After 5 min of work with the water-soaked graphite counter-sample, depending on the applied friction conditions, a reduction in the surface roughness of the stainless steel sample was achieved in the range of 11–18% compared to the initial value. After 30 min of operation, the surface roughness decreased by 3 to 25%. Pilot studies have shown that operating conditions influence the formation of a sliding layer in the stainless steel-expanded graphite tribological contact. This confirms the validity of conducting further research in this area.

Diagnostics of materials by diffraction optical methods

The internal state of the material formed as a result of technological processing, indirectly affects the state of the material surface. A non-contact method of non-destructive control of the state of materials based on a visual analysis of the surface, requires high-quality images which can be obtained either using lens objectives or lenseless technologies. The results of studying image processing obtained by lensless technologies are presented. We used methods for modeling phase masks and image processing based on Gerchberg – Saxton iterative algorithms, adaptive-additive and phase mask rotation based algorithms. Materials such as granite, graphite, sand and carbon steel were analyzed. It is shown that the construction of cameras can provide significant reduction of their dimensions at the same or even improved characteristics. The images obtained using lensless technologies and the proposed methods of image processing also provide a significant increase in the accuracy of visual inspection of materials. The results obtained can be used in refining lensless technologies, improving the quality of images and reducing time of their processing.

Optimal design and experimental research of several-gigawatt multiple electron beam diode

The relativistic klystron amplifier (RKA) is one of the most efficient sources to amplify a high-power microwave signal due to its intrinsic merit of high-power conversion efficiency, high gain and stable operating frequency. However, the transverse dimensions of the RKA dramatically decrease when the operating frequency increases to X band, and the power capacity of the RKA is limited by the transverse dimensions. An X-band multiple-beam relativistic klystron amplifier is proposed to overcome the radiation power limitation. Each electron beam propagates in separate drift tubes and shares the same coaxial interaction cavities in the multiple-beam relativistic klystron amplifier, and the transverse dimensions of the multiple-beam relativistic klystron amplifier are free from the operating frequency restriction and a microwave power of over 1 GW is generated in the experiment. For a high-power electron device, the transmission of electron beam is critical, and the power conversion efficiency of the device is affected. In this paper, we conduct an investigation into the transmission process of the intense relativistic multiple electron beams, and the number of the multiple electron beams is set to be 16. It is found that when the multiple electron beam is transmitted in the device, the electron beam rotates around the center of the whole device, causing the electron beam to deviate from the drift tube channel. At the same time, each electron beam rotates around itself, and the cross section of the electron beam is deformed and expanded. In the improper design of electron beam and drift tube parameters, two kinds of rotating motions cause beam to lose. A multiple-electron-beam diode structure is optimized by the particle-in-cell simulation to reduce beam loss, with the effects of the related factors taken into account. Each pole of the cathodes is made up of graphite and stainless steel. The cathode head is made up of graphite, for the graphite has a lower emission threshold. The cathode base and cathode pole are made up of stainless steel, for the stainless steel has a higher emission threshold. Also the shape and structure of cathode pole, cathode head and anode are optimized to reduce the electric field intensity on the cathode pole and enhance the electric field intensity on the end face of cathode head. At the same time, the electric field distribution of the cathode head is uniform to improve the electron beam emission uniformity. The simulation results demonstrate that the transmission efficiency of multiple electron beams can reach 99%. In the experiment, the transmission efficiency of multiple electron beams is 92% with a beam voltage and beam current of 801 kV and 9.3 kA, respectively.

Voltage Saturation Mechanism in V-I Characteristics for Natural Graphite Brush and Steel Slip-ring

Voltage Saturation Mechanism in V-I Characteristics for Natural Graphite Brush and Steel Slip-ring

Treatment of phenol formaldehyde production wastewater by electrooxidation-electrofenton successive processes

ABSTRACT Treatments of phenol formaldehyde producing wastewater (PFPW) by electrooxidation (EO) and electro-Fenton (EF) successive processes were carried out in a batch electrolytic reactor using graphite (Gr) and stainless steel (Ss) electrodes. After the completion of the EO process, the wastewater was further treated with EF process. The influence of operating variables such as current density, operating time, initial pHi and H2O2 concentration was evaluated for removals of phenol, TOC and COD in PFPW. Gr/Gr, Gr/Ss or Ss/Ss and Ss/Gr electrode pair were used as anode and cathode. The best removal efficiency in the EO process was obtained with Gr/Gr (93%) as compared to Gr/Ss (82%), Ss/Ss (63%) and Ss/Gr (55%). The removal efficiencies for the EO process using Gr-Gr electrode pair were obtained as 93% for phenol, 61% for COD and 44% for TOC at initial pHi 7,5 g/L of NaCl, 50 mA/cm2 and 5 h. In the EF process, the removal efficiencies at pHi 3,5 mA/cm2 and 30 mM H2O2 and 45 min were 100% for phenol, 76% for COD and 59% for TOC. This study provided that the successive processes are an effective method for the removal of phenolic compounds from the wastewater.

Research Regarding Molding of Fuel Cell Bipolar Plates Made of Polymeric-Carbon Composites

Fuel cells are electrochemical devices that convert chemical energy of fuels into electrical energy. Fuel cells were used in NASA space programs to generate energy to satellites and space capsules. Today fuel cells are used to power vehicles including automobiles, forklifts, buses, boats, motorcycles or submarines. Bipolar plates are components of the fuel cell stack and must be highly electrically conductive to obtain a good voltage across the stack and highly thermally conductive to help cooling. Bipolar plates were made of graphite and stainless steel to which additional surface treatments were added to improve properties. In order to reduce the costs of bipolar plates researchers were looking for alternatives: polymeric thermosets and thermoplastics composites. In our paper we analyse the composites polyethylene-carbon and polypropylene-carbon for which we investigated the mechanical properties for the compression-moulded samples. The mechanical, the electrical properties and flow length and the cavity pressure were analysed for the injection moulding in polyethylene-carbon with micro-profiles of 0.5mm x 0.2mm.

Effect of ultrasonic peening technology on the thermal fatigue of rolling mill rolls

In this study, the use of ultrasonic peening technology (UPT) on the rolling mill roll graphite steel GSH48 was surveyed in order to improve some surface mechanical and thermal properties. UPT is one of the newest technologies of severe plastic deformation in which vibratory tool strikes the workpiece surface with continual reciprocating motions, resulting in severe plastic deformation on the surface. This method enhances mechanical and thermal properties like fatigue life and thermal fatigue. Thermal fatigue in the rolling mill rolls causes the growth of crack on the surface and growing that in depth leads to the break of the roll. The influence of the UPT on the improvement of thermal fatigue life of the hot-rolling rolls was investigated by conducting thermal fatigue test in which parameters were adjusted in accordance with the process of hot-rolling. By the simulation and manufacturing of peening vibratory tool, preparation of the process was accomplished including setting up the ultrasonic vibratory tool on lathe machine. According to the standard of related devices, samples were prepared form the surface of roll and the examinations of fatigue, thermal fatigue, and surface topology by atomic force microscopy (AFM) were performed on workpieces in different states before and after the UPT process with one, two, and three passes. The process of ultrasonic peening caused severe plastic deformation on surface layers and prevented from crack growth. The results of this research indicated the rise of the fatigue and thermal fatigue life of the pieces after UPT process.

Graphite Laminated Materials Strength Properties and Energy Characteristics of Polymer Binders

The approach for graphite laminated materials strength properties prediction using contact angle measurements was proposed. The tensile strength of laminated materials made of graphite foil and stainless steel with acrylic and silicone adhesives was measured. It was shown that tensile strength depends on energy characteristics of polymer binders, which can be determined by simple and express wetting method. It was found that the highest values of tensile strength, strength of adhesion and the work adhesion to graphite and stainless steel were provided by acrylic adhesive MBM-5C. The delamination occurred when graphite and stainless steel sheets were connected with low surface energy silicone resin, γ = 23 mJ/m2,<br />what was not able to maintain sufficient adhesion level to the both types of attached surfaces: polar steel and non-polar graphite. It was demonstrated that the calculation of the work of adhesion to polar and non-polar model liquids (water and octane respectively) can be applied to optimize the choice of polymer binder and design of laminated materials. It’s quite important that the proposed technique doesn’t require to determine free surface energy for each type of sheet material which is especially difficult and complex task if laminate consists of several different layers.

Electric arc modeling of the EAF using differential evolution algorithm

ABSTRACTŠtore Steel Ltd. makes more than 1400 steel grades. The highest costs in steel production from scrap stems from the electric arc furnace electric energy consumption. Electrical energy is used to produce heat energy generated by the burning arc between the graphite electrodes and steel scrap. In general, the balanced heat input of all electrodes is essential. Based on the input of thermal energy from all electrodes, also the possibility of occurrence of hot and cold spots in the electric arc furnace can be determined. Perception of and the elimination of the unequal heat load of electrodes have a major impact on reducing operating costs and increasing the efficiency of the electric arc furnace production. Most authors have modeled the arc furnace as an electrical equivalent circuit, where the electric arc is modeled using the macroscopic approach. In this paper, the microscopic approach to the electric arc model is described, where a set of equations (electrical neutrality, Dalton law, Saha–Eggert) was solved using differential evolution algorithm. The results of modeling were practically confirmed by measuring electric parameters (voltage, current, active power) during the electric arc furnace operation. In November 2016, the investment in a new electrode controller using implemented logic will be carried out.

Polyfunctional Coatings on the Basis of Powder Paints Electrostatically Sprayed from the Composite Mixtures Treated in Planetary Ball Mill

The comparative analysis of the structure and properties of composite coatings deposited by electrostatic spraying of nine powder mixtures based on polyester powder paint (PPP), epoxy powder paint (EPP), polyurethane varnish (PUV) with micron size fillers in the form of carbon black (CB), colloidal graphite (CG) and Cr17Ni2 steel have been carried out. The powder mixtures were pre-treated in a planetary ball mill (PBM) to input the maximum amount of functionalizing particles in the coatings. The designed coatings besides carrying out conventional protective (anti-corrosion) functions might be used for removing static electricity and shielding electromagnetic radiation.

Fission Rate Ratios of FCA-IX Assemblies as Integral Experiment for Assessment of TRU’s Fission Cross Sections

At the fast critical assembly (FCA) of JAEA, central fission rate ratios for TRU such as 237 Np, 238 Pu, 239 Pu, 242 Pu, 241 Am, 243 Am, and 244 Cm were measured in the seven uraniumfueled assemblies (FCA-IX assemblies) with systematically changed neutron spectra. The FCA-IX assemblies were constructed with simplicity both in geometry and composition. By virtue of these FCA-IX assemblies where the simple combinations of uranium fuel and diluent (graphite and stainless steel) in their core regions were systematically varied, the neutron spectra of them cover from the intermediate to fast one. Taking their advantages, benchmark models with respect to the central fission rate ratios had been recently developed for the evaluation of the TRU’s fission cross sections. As an application of these benchmark models, the Japanese Evaluated Nuclear Data Library JENDL-4.0 was utilized by a Monte Carlo calculation code. Several results show large discrepancies between the calculation and experimental values. The benchmark models would be well suited for the evaluation and modification of the nuclear data for the TRU’s fission cross sections.

Benchmark models for criticalities of FCA-IX assemblies with systematically changed neutron spectra

New benchmark models with respect to criticality data are established on the basis of seven uranium-fueled assemblies constructed in the ninth experimental series at the fast critical assembly (FCA) facility. By virtue of these FCA-IX assemblies, where the simple combinations of uranium fuel and diluent (graphite and stainless steel) in their core regions were systematically varied, the neutron spectra of these benchmark models cover those of various reactor types, from fast to sub-moderated reactors. The sample calculations of the benchmark models by a continuous-energy Monte Carlo (MC) code showed obvious differences between even the latest versions of two major nuclear data libraries, JENDL-4.0 and ENDF/B-VII.1. The present benchmark models would be well suited for the assessment and improvement of the nuclear data for 235U, 238U, graphite, and stainless steel. In addition, the verification of the deterministic method was performed on the benchmark models by comparison with the MC calculations. The present benchmark models are also available to users of deterministic calculation codes for the assessment and improvement of nuclear data.

In situ TiC–Fe–Al2O3–TiAl/Ti3Al composite coating processing using centrifugal assisted combustion synthesis

The composite coating of a titanium carbide aluminide–alumina-iron composite was synthesized by centrifugal-assisted self-propagating high-temperature synthesis (SHS). The in situ TiC–Al2O3–Fe with intermetallic phases of titanium aluminide (TiAl/Ti3Al) possesses excellent metallurgical properties. This composite was produced from compacted titanium (Ti) and carbon (C) powders in the form of pellets embedded in a tube, which were exposed to very high temperature generated by the thermite Fe2O3 and Al reaction. The process took place in a graphite–steel tube mounted in a centrifugal accelerator machine purposely developed for this function. Functionally graded coating was produced under the centrifugal acceleration field and the product of the thermite reaction (Al2O3 and Fe) infiltrated the TiC pellet and to create a strong, titanium aluminide intermetallic layer. The centrifugal force significantly enhanced both metallurgical alloying and mechanical interlocking between different sample layers during product formation. The purpose of the research addresses the applications of local reinforcement of the ceramic-lined tubes.

Effect of re-irradiation on radiation damage in diamond

The results of the re-irradiation of pre-irradiated diamond in MR and IR-8 reactors at cooling-water temperature are presented. It is shown that the greater the expansion recovery of the diamond lattice after annealing, the more intense re-expansion on re-irradiation is. It is also shown that the more intense the re- and pre-irradiation are, later the onset of the second stage of damage in diamond – swelling and amorphization – is. It is conjectured that this effect is related with radiation γ-annealing. Experimental results confirming the presence of the identical effect in graphite and vessel steel are presented.

A novel fabrication method for TiC–Al2O3–Fe functional material under centrifugal acceleration

Compacted powders of titanium (Ti) and carbon (C) in form of pellets were exposed to a massive amount of heat generated from the thermite reaction of Fe2O3 and Al in a graphite–steel tube mounted in a developed centrifugal accelerator machine. The centrifugal force facilitated the formation of multi-component products during the process. Titanium carbide (TiC) product is joined to an Al2O3–Fe layer, which are the products of the thermite reaction. The existence of centrifugal acceleration had a significant effect on both metallurgical alloying and mechanical interlocking between different layers of the sample to form a functional material. A mathematical model developed for this experiment to describe the speed rate of iron infiltration inside the TiC product as well as viscosity rate variation was presented. The composition, microstructure and mechanical properties confirmed the model.

Effects of the Cooling Rate on the Solidification Microstructure of Cu-Ni Alloy

The effect of cooling rate on the solidification microstructure of Cu-Ni alloy is investigated here. The Cu-Ni alloy was prepared in a main frequency furnace with three different molds made of silica sand, graphite, and low carbon steel in the foundry. The simulation software of diathermanous-flowing-stress coupling PROCAST is used to simulate the Cu-Ni alloy solidification process about temperature field with the three molds. The microstructures of the alloys have been studied through the optical microscopy (OM), the scanning electron microscopy (SEM), together with the energy dispersive spectroscopy (EDS).The results show that the grain average size and the primary and secondary dendrite arm space were obviously reduced with the increase of cooling rate. The dendrite and interdendrite element segregation also decreases with increasing cooling rate.

A slide-type multianvil ultrahigh pressure apparatus and calibrations of its pressure and temperature

A slide-type ultrahigh pressure apparatus with 6/8 anvils is described. The three-supporting pillars of the main framework and the slide-type multi-anvils have conformable mechanical symmetry. Under the loading uniaxial pressure, the first-stage anvils can be self-corrected and run with excellent synchronicity and reproducibility. In the present experiments, the edge length of pyrophyllite octahedron is 125 mm and the truncation edge length of tungsten carbide anvil is 8 mm. The cell pressure was calibrated at room temperature by means of the known pressure-induced phase transitions of Bi and ZnTe at 255, 77, 96 and 120 GPa. The cell temperature under 10 GPa was measured up to 1560 ℃ by WRe3-WRe25 thermocouple. The temperature calibration was reconfirmed and extended to the higher range by observation of diamond formation on the interface between graphite heater and steel plug, and by comparison of the variational details of recorded data and the Fe—C phase diagram, and then the axial temperature gradient was estimated to be about 21 ℃/mm.

Decolorization of Congo Red with Three-Dimensional Flow-By Packed-Bed Electrodes

The electrochemical removal of the color of the dyestuff Congo Red was investigated experimentally by using packed graphite anodes as well as packed graphite or C-304 stainless steel cathodes in an undivided reactor. The effects of the applied apparent current density, the amount of chloride ion addition, the pH value of the solution, the cathode material, the operating temperature, the volumetric flow rate and the initial concentration of Congo Red on the removal efficiencies were investigated in this study. Experimental results showed that the main pathway of color removal was by the hypochlorite generated in-situ at the anodes. Compared with the indirect oxidation, the color removal due to direct oxidation was insignificant. Cathodic oxidation by using graphite cathodes had little influence on the removal rate in an undivided electrochemical cell.

433 球状黒鉛鋼の機械的性質に及ぼす Ni 添加の影響

Graphite steel has spheroidal or globular form of graphite in steel. The spheroidal graphite cast steel is rich in castability and high damping capacity compared with carbon steel. The effect of mechanical properties and heat-treatment of Fe-1.3%C-1.8%Si-0∿6%Ni investigated. Tensile strength of air-cooled specimen with the Ni free specimen was 870MPa. In the air-cooled, tensile strength decreased with increased in the Ni. In the furnace-cooled, tensile strength increased with increased in the Ni. Microstructure of air cooled specimen to 2%Ni was a pearlite and ferrite around the graphite. The matrix becomes the martensite at 4%Ni.

Explosive cathode gyrotron experiments

Experiments have investigated the behavior of explosive emission cathode gyrotrons using cylindrically symmetric coaxial diodes with centrally located knife-edged cathode and conical anode. Voltage probes and current shunts were exploited to monitor the diode electrical behavior when driven by a 3 /spl mu/s 1/e time Marx power supply (up to 150 kV). Temporal reference signals permitted comparison of the diode's electrical evolution with the simultaneously measured microwave output signal from the gyrotron. The microwave output pulse duration was found to depend on the diode gap spacing (in the range 16-27 mm), the cavity magnetic field (range 1.3-3.3 T) and the cathode material, the termination being caused by the decay of the accelerating potential across the diode and the disruption of the diode geometry. The ratios of the cathode flare expansion velocities for graphite, copper and stainless steel cathodes were estimated as (1:(1.3/spl plusmn/0.2):(2.2/spl plusmn/0.5)) with a corresponding change in the duration of the microwave output signal [((590/spl plusmn/17):(414/spl plusmn/25):(325/spl plusmn/10)) ns at 2.6 T]. Preliminary results are reported of recent experiments which have compared the optical emissions from the diode region during pulsed gyrotron operation with the simultaneously recorded diode electrical behavior and the gyrotron microwave output.