FedFreeze: A dual-phase layer freezing framework for federated learning

Microstructure and chemistry of the arc ion-plated CrN coatings oxidized in air at temperatures ranging from 300 to 800 °C for 60 min were analyzed by x-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and Auger electron spectroscopy (AES). The CrN coatings were prepared by cathodic arc ion plating deposition on a type 304 stainless steel with a Cr interlayer. The XRD result shows that oxidation of the CrN-coated steel above 500 °C produces two new phases, Cr2O3 and β-Cr2N, and the amount of both phases increases with the oxidation temperature. Cross-section TEM shows three distinct regions including the steel substrate, the Cr interlayer, and the CrN coating in the as-deposited specimen, in which the CrN layer exhibits a columnar structure and preferred orientation. Oxidation of the CrN-coated steel at high temperatures produces an oxide layer, Cr2O3, on the coating surface, and the underlayer is a mixture of CrN and β-Cr2N phases. Unlike the as-deposited specimen, the dual phase layer in the oxidized specimens has an equiaxed grain structure and the average grain size of the layer increases with the oxidation temperature. In addition, pronounced grain growth in the dual phase layer near the coating surface is observed in the specimen heat-treated at 800 °C. Elemental analyses of the CrN coating near the free surface by EELS and AES reveal that the O/N ratio of the coating and the thickness of the oxide layer increase with the oxidation temperature.

New Ti/β-Ti alloy laminated composite processed by powder metallurgy: Microstructural evolution and mechanical property

When a surface of a titanium disk was melted in an atmosphere of pure nitrogen using a 3D Micro Welder which was designed by the present authors, the surface was nitrided to a depth of 90 to 260μm depending on the arc current of 6 to 24 A. The concentration of nitrogen in the nitrided layer was approximately 50 mol% at the surface, and the concentration decreased as the distance from the surface increased. A TiN layer was formed at the surface, and beneath the TiN layer, a dual phase layer of TiN and α-Ti was formed. Vickers hardness was approximately 1800 in the TiN layer and it varied from 900 to 200 in the dual phase layer as the distance from the surface increased.

A periodic-layered structure was observed in solid-(Cr, Fe)2B/liquid-Al diffusion couple at 750 °C. The interface morphology, the reaction products, and the potential formation mechanism of this periodic-layered structure were investigated using an electron probe microanalyzer (EPMA), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS). The results indicate that the reaction between (Cr, Fe)2B and liquid Al is a diffusion-controlled process. The formation of intermetallics involves both the superficial dissolution of Fe and Cr atoms and the inward diffusion of Al at the interface. The layered structure, as characterized by various experimental techniques, is alternated by a single FeAl3 layer and a (FeAl3 + Cr3AlB4) dual-phase layer. A potential mechanism describing the formation process of this periodic-layered structure was proposed based on the diffusion kinetics based on the experimental results.

Phase constitution control of plasma nitrided layer and its effect on wear behavior under different loads

Discharge homogeneity is one of the dominant factors affecting cathode lifetime. In this work, the arc ablation behavior of a zirconium cathode is investigated in air and argon atmospheres. Homogeneous discharge processes are observed in air, while poor discharge homogeneity with scattered cathode spots is found in argon. The homogeneous discharge process is related to the layered structure at the discharge center. The surface zirconium oxide layer stabilizes the arc foot and reduces the effective work function. A dual-phase layer underneath, consisting of zirconium oxides and zirconium, enables the transition from the zirconium matrix to the surface oxide layer. The sustainable discharge behaviors are realized by the balance in the cathode, which is created by the ablation of surface zirconium oxides and the oxidization of zirconium in the dual-phase layer.

Hydrogen production with carbon dioxide capture by dual-phase ceramic-carbonate membrane reactor via steam reforming of methane

Mechanism of reheat cracking in electron beam welded Ti2AlNb alloys

Characterization of the CrN coatings oxidized in air at temperatures ranging from 300 to 800°C for 60 min was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Auger electron spectroscopy (AES). The CrN coatings were prepared by cathodic arc ion plating deposition on a type AISI 304 stainless steel with a Cr interlayer. XRD result shows that oxidation of the CrN-coated steel above 500°C produces two new phases, and and the amount of both phases increases with the oxidation temperature. A noticeable change in the surface morphology of the coatings was observed by SEM in the specimens oxidized at temperature above 600°C. Cross-sectional TEM reveals that oxidation of the CrN-coated steel at high temperatures produces an oxide layer, on the coating surface, and the underlayer is a mixture of CrN and phases. Unlike the as-deposited specimen, the dual-phase layer in the oxidized specimens has an equiaxed grain structure and the average grain size of the layer increases with oxidation temperature. Auger depth profiling of the oxidized CrN coatings at various temperatures reveals the elemental distributions in the coatings and the thickness of the oxide layer near the free surface, from which the activation energy of oxidation for the CrN coatings is calculated to be 1.63 eV. © 2002 The Electrochemical Society. All rights reserved.

Deformation behavior of brittle/ductile multilayered composites under interface constraint effect

An increase in the utilization efficiency of CaO, one of the major fluxing agents used in various steelmaking processes, is required to reduce the amount of discharged slag and energy consumption of the process. The authors have intensively focused on the development of innovative dephosphorization process by using so called “multi-phase flux” composed of solid and liquid phases. This article summarizes the research on the above topic done by the authors, in which the formation mechanisms of P2O5-containing phase during CaO or 2CaO·SiO2 dissolution into molten slag, the phase relationship between solid and liquid phases at equilibrium, and thermodynamic properties of P2O5-containing phase have been clarified. The reactions between solid CaO or 2CaO·SiO2 and molten CaO-FeO x -SiO2-P2O5 slag were observed by dipping solid specimen in the synthesized slag at 1573 K or 1673 K. The formation of the CaO-FeO layer and dual-phase layer of solid 2CaO·SiO2 and FeO x -rich liquid phase was observed around the interface from the solid CaO side toward the bulk slag phase side. Condensation of P2O5 into 2CaO·SiO2 phase as 2CaO·SiO2-3CaO·P2O5 solid solution was observed in both cases of CaO and 2CaO·SiO2 as solid specimens. Measurement of the phase relationship for the CaO-FeO x -SiO2-P2O5 system confirmed the condensation of P2O5 in solid phase at low oxygen partial pressure. The thermodynamics of 2CaO·SiO2-3CaO·P2O5 solid solution are to be clarified to quantitatively simulate the dephosphorization process, and the current results are also introduced. Based on the above results, the reduction of CaO consumption, the discharged slag curtailment, and energy-saving effects have been discussed.

TECHNOLOGY HARDENING TREATMENT FOR THE SLIDING SUPPORTS OF DRILL BITS O. V. Sizova, A. V. Kolubaev, V. I. Koveshnikov, G. V. Trusova, and S. Yu. Tarasov UDC 622.4.051 An increase in the driving rate and a reduction in expenditures for the drilling of wells in modern oil fields depend on the longevity and operating efficiency of the drill bits. The support is an important bit component, which determines the reliability of the structure on the whole. The most common problem in constructing the sliding supports consists in creating sur- faces of high hardness, which are uniform throughout the structure and which are formed from carburized and hardened steels [i] and composition anti-friction materials (for exam- ple, stellite) having a low coefficient of friction and high wear resistance [2]. Broad use of this type of hard-alloy materials as wear-resistant facings suppresses cracking of the facing layer, which significantly lowers the strength and fatigue properties of the sliding surface and is frequently the cause of so-called seizure due to separation of par- ticles in the failed layer. The firm Hughes Tool (United States) has adopted one of the recent technical solutions directed toward support surfaces with a high hardness. According to [3], the sliding sur- face of the bit journal is borided, as a result of which the strength and wear resistance of the support is increased by many times. This form of case hardening (CH) is not em- ployed in the domestic bit industry due to inadequate technical development of the method. We are proposing an original method for the complex boriding of the surface of a bit journal to replace the facing. The developed technology is a variety of CH and makes it possible to produce a wear-resistant layer of from 0.04 to 0.15 mm deep by the method of diffusion saturation with boron and other alloying elements. The studies were conducted on precarburized steel 15N3MA. Commercial boron carbide (GOST 5744-85) with a filler formed from aluminum oxides and other metals and commercial carbon was used as the boriding agent. The boriding was carried out over a period of 5 h0 After boriding, the specimens were subjected to hardening heat treatment. The phase com- position and thickness of the borided layer were determined by the metallographic method of "color etching" [4], from the results of microhardness measurements, and with the use of x-ray spectral analysis. The microstructure of the boride layers produced at different temperatures of the pro- cess is shown in Fig. i. The dark color belongs to the Fe2B phase, and the lighter color on the surface to the FeB phase. Attention is turned to the increase in the content of the FeB phase with increasing CH temperature. The maximum thickness of the FeB phase, as mea- sured over the ends of the boride needles, reached 60 ~m at a temperature of 940~ and the overall thickness of the dual-phase layer amounted to 160 ~m (see Fig. la). Only indi- vidual particles of the FeB phase are exposed at a treatment temperature of 920~ (see Fig. Ib), and iron monoboride is absent at 900~ (see Fig. le). The microhardness of the bo- rides under a loading of 1N amounted to H u = 19500-21500 MPa for the FeB, and H~ = 14000- 17000 MPa for the Fe2B. A characteristic feature of the boride layer produced at temperatures of 900 and 920~ is the "serration" of its structure, in the bed of whose roots a phase that cannot be tin- ted during color etching is present. This phase is manifested in the carburized layer as a result of the boron repelling the carbon back into the depths of the metal, and is, most likely, ultradisperse martensite. Its microhardness, as measured under a load of 1 N, is H u = 10000-11000 MPa. By varying the CH temperature, therefore, it is possible to obtain qualitatively dif- ferent structures of the boride coatings. The phase composition of the boride layer assumes Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 4, pp. 25-27, April, 19937 188 0009-2355/93/0304-0188512.50 9 1993 Plenum Publishing Corporation

The impact of post-treatments on the brittleness and wear resistance of borided 8 % Cr steel

CO2-permselective membrane reactor for steam reforming of methane

In this paper, a two-dimensional particle image velocimetry (PIV) system was used to examine the f/2 stripe pattern forming in a vertically vibrated granular layer. Since the PIV sampling frequency does not match with the vibrating frequency, a special identification-coupling method was adopted to combine the images taken in different cycles to offer the information in one complete cycle. The measured velocity vectors showed exactly the particle motions at various stages of a motion cycle, illustrating the alternating peaks and valleys on the layer top. Furthermore, quantitative results on the temporal evolution of velocity profiles were obtained and some other interesting phenomena were observed, such as the appearance of local structures (e.g., dual-phase layer structure) and the moving feature of the “standing point.” The mechanism accounting for the occurrence of stripes on the surface is discussed.