Investigation of the variation in the size of samples made of 5СNM steel under thermal diffusion saturation with powder mixtures containing boron and copper

2021 ◽  
pp. 498-502
Author(s):  
S.A. Lysykh ◽  
V.N. Kornopol’tsev ◽  
U.L. Mishigdorzhiyn ◽  
Yu.P. Kharaev ◽  
D.E. Dasheev
Keyword(s):  
Thermal Diffusion ◽  
Powder Mixture ◽  
Chemical Elements ◽  
Alloyed Steel ◽  
Diffusion Saturation ◽  
Powder Mixtures ◽  
Copper Diffusion ◽  
Diffusion Layers ◽  
Acicular Structure ◽  
Steel 5Khnm

The change in the dimensions of parts after diffusion saturation of alloyed steel 5KhNM with boron and copper is investigated. Diffusion layers obtained on samples with different compositions of the saturating mixture are described. It is shown that when carrying out experiments on saturation of samples in a medium of powders with boron and copper, diffusion layers with an acicular structure with a thickness of 220...330 μm are obtained, and the increase in the observed size was from 44 to 135 μm, depending on the composition of the powder mixture. The properties of diffusion layers have been studied, including the distribution of microhardness and chemical elements at different distances from the surface.

Diffusion Layers with Ti and Ti+Al Formed on 316L Austenitic Steel by a Pack Cementation Procedure

2011 ◽  
Vol 312-315 ◽  
pp. 13-19 ◽  
Author(s):  
Iulia Mirela Britchi ◽  
Mircea Olteanu ◽  
Niculae Ene ◽  
Petru Nita
Keyword(s):  
Activation Energy ◽  
Powder Mixture ◽  
Pack Cementation ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Diffusion Coatings ◽  
Diffusion Layers ◽  
316L Steel ◽  
Temperature Activation

Pack cementation procedure implies the use of a powder mixture containing the diffusive elements, which in our case are either Ti or Ti+Al, Al2O3 and NHCl as activator. In the case of titanizing the powder mixture contained 77% in weight Ti, while for alumino-titanizing Al/Ti = 1/5 ratio was employed. NH4Cl content was 3% in weight in all cases. Aluminium additions to the powder mixtures led to a decrease of the process temperature. Activation energy for the aluminizing of austenitic 316L steel is 73.87 KJ/mol, much smaller than for the titanizing, 257.86 KJ/mol. Activation energy for alumino-titanizing, in the same conditions, is 146.01 KJ/mol. All diffusion coatings, in the Ti – 316L and Ti+Al – 316L couples are formed of two layers having different structures and compositions. All couples were investigated by optical microscopy, electron microscopy (SEM and EDX), X-ray diffraction and microhardness trials.

scholarly journals Малогазовая детонация в низкоплотных механоактивированных порошковых смесях

2019 ◽  
Vol 89 (6) ◽  
pp. 821
Author(s):  
С.А. Рашковский ◽  
А.Ю. Долгобородов
Keyword(s):  
Experimental Data ◽  
Shock Wave ◽  
Energy Release ◽  
Powder Mixture ◽  
Powder Compaction ◽  
Mutual Friction ◽  
Low Density ◽  
Powder Mixtures ◽  
Release Wave ◽  
Fuel Particles

Experimental data on supersonic self-sustaining propagation of the energy release wave in low-density mechanically activated powder mixtures are analyzed. Various mechanisms that may be responsible for this process are analyzed, and a mechanism for the detonation-like propagation of the reaction in powder mixtures is proposed. It is shown that under certain conditions this process has all the signs of detonation and should be recognized as one of the types of detonation. It is shown that this type of detonation is fundamentally different from the classical "ideal" detonation, for example, in gases: instead of a shock wave, a compaction wave propagates through the powder mixture, in which there is basically no compression of the particle material, but powder compaction occurs due to the mutual rearrangement of particles. In this case, the initiation of a chemical reaction occurs due to the mutual friction of the oxidizer and fuel particles in the powder compaction wave.

Investigation of the Structure and Distribution of Chemical Elements between the Phases of Hard Alloys of the Cr3C2-Ti System, Obtained at Various Modes of Explosive Compaction

2020 ◽  
Vol 992 ◽  
pp. 487-492
Author(s):  
V.O. Kharlamov ◽  
Aleksandr Vasilevich Krokhalev ◽  
S.V. Kuz’min ◽  
V.I. Lysak
Keyword(s):  
Phase Composition ◽  
Powder Mixture ◽  
Chemical Interaction ◽  
Chemical Elements ◽  
Equilibrium Phase ◽  
Hard Alloys ◽  
Explosive Compaction ◽  
Thermo Calc Software ◽  
Equilibrium Phases ◽  
Explosive Pressing

The Article presents the findings of the studies of the microstructure, chemical and phase composition of the Cr3C2-Ti system alloys obtained by the explosion. Scanning electron microscopy, energy dispersive and x-ray diffraction analyses were used. The program Thermo-Calc software was used to calculate the equilibrium phases. The phase composition of the compact was shown to fully correspond to that of the initial powder mixture during explosive pressing in the modes of heating from 300 ̊С to 600 ̊С. When heated above 600 ̊С, the chemical interaction of the initial components begins with the formation of new boundary phases. Meanwhile, there is a change in the sample destruction nature and a significant increase in hardness, which points to the hard alloy consolidation. The increase in the powder mixture heating in shock waves to 1000 ̊С leads to intensive macrochemical interaction of the powder mixture components and to formation of an equilibrium phase composition. The established temperature limits determine the most appropriate parameters of shock-wave loading when producing hard alloys by explosive pressing.

Structure of diamond-matrix interface and durability of diamond tool obtained by diamond metallization with chromium during WC–Сo briquette sintering with copper impregnation

2018 ◽  
pp. 64-75 ◽  
Author(s):  
P. P. Sharin ◽  
M. P. Akimova ◽  
S. P. Yakovleva ◽  
V. I. Popov
Keyword(s):  
Thermal Diffusion ◽  
Powder Mixture ◽  
Diamond Tool ◽  
Shielding Effect ◽  
Diamond Surface ◽  
Specific Productivity ◽  
Matrix Interface ◽  
Abrasive Wheel ◽  
Hybrid Technology ◽  
Diffusion Metallization

The paper studies the structure, elemental and phase composition of the diamond-matrix interface in a diamond tool for abrasive wheel dressing manufactured using a new hybrid technology that combines thermal diffusion metallization of diamond with chromium and sintering of a matrix based on WC–6%Co carbide powder mixture with copper impregnation in a single cycle of vacuum furnace operation. During matrix sintering, the compact arrangement of chromium powder particles around diamond grains and the shielding effect of copper foil create favorable conditions that ensure the thermal diffusion metallization of diamond. Scanning electron microscopy, X-ray diffraction, and Raman spectroscopy show that temperature-time modes and sintering conditions specified in the experiment provide for a metal coating chemically bonded to diamond that is formed on the diamond surface and consists of chromium carbide phases and cobalt solid solution in chromium providing durable diamond retention in the copper-impregnated carbide matrix. In this case, matrix structure and microhardness except for areas directly adjacent to the diamond-matrix interface remain the same as for the matrix of a powder mixture sintered without chromium. Comparative tests of similar diamond dressing pens were carried out and showed the high effectiveness of the hybrid technology in obtaining diamond-containing composites intended for tool applications. It is shown that the specific productivity of a pen prototype made using the hybrid technology was 51,50 cm3/mg when dressing a grinding wheel of green silicon carbide that is 44,66 % higher than the similar indicator for the sametype check pen made by the traditional method.

Vacuum Repair Brazing of the Inconel 939 Superalloy

2008 ◽  
Vol 51 ◽  
pp. 71-78 ◽  
Author(s):  
D.K. Wang ◽  
H.C. Wu ◽  
R.K. Shiue ◽  
C. Chen
Keyword(s):  
Chemical Composition ◽  
Oxide Film ◽  
Oxidation Resistance ◽  
Powder Mixture ◽  
Eutectic Temperature ◽  
Early Stage ◽  
Isothermal Solidification ◽  
Catastrophic Failure ◽  
Powder Mixtures ◽  
Residual Melt

Vacuum repair brazing of Inconel 939 using various ratios of DF3 and Rene 80 powder mixtures has been performed in this study. The porosity of the brazed zone is decreased as the amount of DF3 is increased in the powder mixture. At least four phases are observed in the brazed zone including chromium borides, sparse carbides, Ni-rich matrix and eutectic phases. Primary chromium borides are widely observed at the early stage of repair brazing. Dissolution of the Ni from the Rene 80 powder into the molten braze results in isothermal solidification of the residual melt. The chemical composition of the residual melt subsequently moves towards the lowest eutectic temperature, and the eutectic is finally formed in brazing. The oxidation resistance test is performed at 1000oC. Extensive spalling of the oxide film begins at 144 h, and catastrophic failure of the oxide film is observed at 1272 h. The oxidation resistance of the brazed zone is significantly degraded due to the formation of chromium borides in the brazed zone.

scholarly journals Diffusion Coatings as Corrosion Inhibitors

2016 ◽  
Vol 3 (1) ◽  
pp. 40-44
Author(s):  
Radoslav Ivanov ◽  
Tsveteslava Ignatova-Ivanova
Keyword(s):  
Corrosion Resistance ◽  
Diffusion Saturation ◽  
Metal Base ◽  
Diffusion Coatings ◽  
Diffusion Layers ◽  
Steel Container ◽  
Structure Thickness ◽  
Metal Products ◽  
Composition Structure ◽  
Harmful Effects

Abstract Corrosion is the cause of irretrievable loss of huge amounts of metals and alloys. The harmful effects of corrosion can be reduced significantly by applying appropriate methods of corrosion protection. One method to protect metals against corrosion is the formation of diffusion coatings on them. High corrosion resistance is typical for the boride diffusion layers. Aluminothermy is one of the main methods for diffusion saturation of the surface of metal products with various elements, including boron, and under certain conditions with aluminum, too. Samples of steel 45 were put to aluminothermic diffusion saturation with boron in a pressurized steel container at a temperature of 1100K, for 6 hours in powdered aluminothermic mixtures. The content of В2О3 in the starting mixtures decreased from the optimum - 20% to 0%, and the content of Al and the activator - (NH4)2.4BF3 is constant, respectively 7% and 0.5%. Al2O3 was used as filler. The borided samples were tested for corrosion resistance in 10% HCl for 72 hours. The results show that their corrosion resistance depends on the composition of the starting saturating mixture (mainly on the content of В2О3), and respectively on the composition, structure, thickness and degree of adhesion of the layer to the metal base.

Kinetics of Low Temperature Nitriding of Precipitation Hardened Stainless Steel

2011 ◽  
Vol 312-315 ◽  
pp. 530-535 ◽  
Author(s):  
Paweł Kochmański ◽  
Jolanta Baranowska
Keyword(s):  
Stainless Steel ◽  
Low Temperature ◽  
Chemical Elements ◽  
Nitrided Layer ◽  
Nitriding Time ◽  
Diffusion Layers ◽  
Optical Spectrometry ◽  
Xrd Phase Analysis ◽  
Time Changes ◽  
Kinetics Of

The paper presents results of research on nitrided layers on precipitation hardened stainless steel, known also as 1RK91 (Sandvik NanoflexTM). Samples were subjected to low temperature nitriding. The influence of nitriding parameters on nitriding kinetics was investigated. The nitriding process was carried out in a mixture of NH3 50% and products of its dissociation as well as in 100% ammonia atmosphere at temperature range 425-475°C. To investigate the kinetics of nitrided layer formation, the nitriding time changes between 2 and 8 h. The obtained diffusion layers were examined using the following methods: light and scanning electron microscopy, XRD phase analysis. The distribution profiles of selected chemical elements were acquired using optical spectrometry GDOES.

THE SURFACE AND INTERFACE PROPERTIES OF VANADIUM CARBIDE COATING PREPARED BY THERMAL DIFFUSION PROCESS

2011 ◽  
Vol 10 (01) ◽  
pp. 183-190 ◽  
Author(s):  
DEJUN KONG ◽  
CHAOZHENG ZHOU
Keyword(s):  
Thermal Diffusion ◽  
Vanadium Carbide ◽  
Chemical Elements ◽  
Energy Dispersive Spectrometer ◽  
Salt Bath ◽  
Bonding Interface ◽  
Surface And Interface ◽  
Coating Surface ◽  
Bonding Method ◽  
Vanadium Carbide Coating

Vanadium carbide (VC) coating is prepared with Thermal Diffusion (TD) method in the salt bath, and its surface-interface microstructures and energy spectrums were observed with Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS), respectively, and the distributions of C , V , Cr , Si , Fe , and Mo in VC coating interface are analyzed. Its interfacial and bonding methods are discussed, and the bonding micromechanism of VC coating in its bonding interface by TD process is analyzed. The experimental results show that the structure of coating surface by TD is single-phase, that is composed of V and C elements, and no other elements, the chemical elements such as V , Cr , C Si , Fe , Mo are the grade distributed in its bonding interface; its bonding method is metallurgical status; microhardness of coating-substrate is the grade distribution, which is direct ratio with the V distribution, microhardness of the coating surface is 3050–3200 HV, and the effect of TD process on roughness of cold-working die surface is little.

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