Features of the Structure Formation of Diffusion Boride Layers upon Preliminary Activation

2021 ◽  
Vol 903 ◽  
pp. 183-189
Author(s):  
Yulia Usherenko ◽  
Viktor Mironov ◽  
Vladimir Dashkevich
Keyword(s):  
Surface Treatment ◽  
Structure Formation ◽  
Diffusion Layer ◽  
Powder Composition ◽  
Diffusion Layers ◽  
Superdeep Penetration ◽  
High Boron ◽  
Preliminary Activation

The features of the structure formation of diffusion layers obtained by technology, including preliminary surface treatment of steel products made of U8 steel and subsequent boriding in powder media, have been investigated. The pretreatment consisted of dynamic alloying in the superdeep penetration (SDP) mode with a SiC-based powder composition. As a result, the thickness of the diffusion layer increases, its porosity decreases, and the proportion of the high-boron FeB phase in the layer increases.

scholarly journals Activation of diffusion during the formation of boride layers on the surface of steel parts

2021 ◽  
pp. 94-99
Author(s):  
S. M. Usherenko ◽  
V. G. Dashkevich ◽  
Yu. S. Usherenko
Keyword(s):  
High Temperature ◽  
Chemical Composition ◽  
Surface Activation ◽  
Powder Composition ◽  
Diffusion Layers ◽  
Superdeep Penetration ◽  
Quantitative Characteristics ◽  
Diffusion Boriding ◽  
High Boron ◽  
Preliminary Activation

The features of structure formation of diffusion layers obtained by the technology, including preliminary surface treatment of steel products and subsequent thermal diffusion boriding in powder media, have been investigated. Pretreatment consisted in surface activation by superdeep penetration with a powder composition based on SiC of steel samples made of У8 steel. The features of the activation zones and their distribution over the surface are noted. The features of the activation zones and their quantitative characteristics are noted. A structural analysis of the obtained diffusion layers for the variants of low-temperature (650 °C) and high-temperature (920 °C) boration has been carried out. The chemical composition of the layer and the distribution of the main elements in it are analyzed. In both cases, a change in morphology was noted, consisting in the formation of a more compact diffusion layer and rounding of boride needles in the zone adjacent to the base metal. An increase in the layer thickness by 20–50 % and an increase in the proportion of the high-boron FeB phase relative to the variant of borating without preliminary activation were established.

Effect of chemical heat treatment on cavitation erosion resistance of stainless steel

2019 ◽  
Vol 233 (11) ◽  
pp. 1753-1762
Author(s):  
Hongqin Ding ◽  
Shuyun Jiang ◽  
Jiang Xu
Keyword(s):  
Stainless Steel ◽  
Mass Loss ◽  
Diffusion Layer ◽  
Cavitation Erosion ◽  
Erosion Resistance ◽  
304 Stainless Steel ◽  
Chemical Heat ◽  
Electrochemical Test ◽  
Diffusion Layers ◽  
Cavitation Erosion Resistance

The purpose of this paper is to study the effect of chemical heat treatments on cavitation erosion resistance of the 304 stainless steel. Three types of diffusion layers are prepared on the 304 stainless steel using gas nitriding, gas carburizing, and carbonitriding treatments. Phase composition and surface microstructure of the diffusion layers are characterized by X-ray diffraction and scanning electron microscopy. And then, the cavitation erosion behavior of the diffusion layers are tested and compared with the one of the 304 stainless steel. The cavitation test is performed in an ultrasonic vibration system integrated with an electrochemical workstation. The mass loss, scanning electron microscopic morphology, and electrochemical test are adopted to assess the surface damage of the diffusion layers. A measurement for the mechanical properties of the diffusion layers shows that the hardness and the elastic modulus of the gas nitrided diffusion layer, carbonitrided diffusion layer, carburized diffusion layer, and 304 stainless steel are 5.3 GPa and 260 GPa, 4.2 GPa and 236 GPa, 4.0 GPa and 210 GPa, 2.5 GPa and 193 GPa, respectively. A cavitation erosion test of 14 h shows that mass loss of the gas nitrided diffusion layer, carbonitrided diffusion layer, carburized diffusion layer, and 304 stainless steel is 5.19 mg, 8.97 mg, 14.37 mg, and 6.62 mg, respectively. The electrochemical test results also indicate that the gas nitrided diffusion layer has a higher corrosion resistance than the carburized diffusion layer, carbonitrided diffusion layer, and stainless steel under cavitation erosion condition. As a conclusion, the gas nitrided diffusion layer is capable of enhancing the cavitation erosion resistance of the stainless steel, while the carburized diffusion layer and carbonitrided diffusion layer increases the mass loss of the stainless steel under cavitation erosion condition.

Derivation of Temperature-Estimation Equation Based on Microstructural Changes in Coatings of In-Service Blades of Gas Turbines

2010 ◽  
Author(s):  
Mitsutoshi Okada ◽  
Tohru Hisamatsu ◽  
Terutaka Fujioka
Keyword(s):  
High Temperature ◽  
Diffusion Layer ◽  
Gas Turbines ◽  
Aluminum Content ◽  
Oxide Formation ◽  
Diffusion Layer Thickness ◽  
Temperature Estimation ◽  
Diffusion Layers ◽  
Barrier Coating ◽  
Trailing Edges

A CoNiCrAlY-coated blade of an in-service gas turbine is analyzed, and a diffusion layer is formed along the boundary between the coating and the substrate due to the interdiffusion in the middle and tip of the blade. Such a layer is not observed in the vicinity of the blade root because of a comparatively low temperature during the operation. Coated specimens are prepared from the portions of the blade devoid of the diffusion layers, and the specimens are exposed to a high temperature in air. On the basis of the increase in the diffusion layer thickness, an equation for estimating the temperature of the blade is derived. Analysis of another in-service blade with a thermal barrier coating (TBC) is carried out. The aluminum-content decreases below the bond coat surface due to Al diffusion caused by the Al-oxide formation. This results in the formation of an Al-decreased layer (ADL) along the leading and trailing edges. The ADL is not observed at the center of the blade chord. The specimens are extracted from the portions of the blade that are devoid of ADL, and they are subjected to a high temperature in air. On the basis of the increase in the ADL thickness, a temperature-estimation equation is derived.

Influence of Water Behavior in the Gas Diffusion Layer on the Performance of PEMFC

2004 ◽  
Author(s):  
Gu-Gon Park ◽  
Young-Jun Sohn ◽  
Sung-Dae Yim ◽  
Tae-Hyun Yang ◽  
Young-Gi Yoon ◽  
...  
Keyword(s):  
Diffusion Layer ◽  
Driving Forces ◽  
Single Cells ◽  
Gas Diffusion Layer ◽  
Gas Diffusion ◽  
Gas Diffusion Layers ◽  
Operation Conditions ◽  
Diffusion Layers ◽  
Water Transportation ◽  
Water Behavior

The affect of water behavior on the performance of the polymer electrolyte membrane fuel cell (PEMFC) was investigated experimentally. To understand the water transportation phenomena systematically, the gas diffusion layers were divided into two parts: the gas diffusion medium (GDM) and the micro-layer (ML). In this work, different Teflon (PTFE) contents in the GDM were intensively investigated under various single cell operation conditions. Current-Voltage (I-V) performance curves of single cells were compared and analyzed with respect to water transportation in the GDM. Through the results of this work, the dominant driving forces of the water transportation in the gas diffusion layer were determined which aids in designing the gas diffusion layers.

Derivation of Temperature-Estimation Equation Based on Microstructural Changes in Coatings of In-Service Blades of Gas Turbines

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Mitsutoshi Okada ◽  
Tohru Hisamatsu ◽  
Terutaka Fujioka
Keyword(s):  
High Temperature ◽  
Diffusion Layer ◽  
Gas Turbines ◽  
Aluminum Content ◽  
Oxide Formation ◽  
Diffusion Layer Thickness ◽  
Temperature Estimation ◽  
Diffusion Layers ◽  
Barrier Coating ◽  
Trailing Edges

A CoNiCrAlY-coated blade of an in-service gas turbine is analyzed, and a diffusion layer is formed along the boundary between the coating and the substrate due to the interdiffusion in the middle and tip of the blade. Such a layer is not observed in the vicinity of the blade root because of a comparatively low temperature during the operation. Coated specimens are prepared from the portions of the blade devoid of the diffusion layers, and the specimens are exposed to a high temperature in air. On the basis of the increase in the diffusion layer thickness, an equation for estimating the temperature of the blade is derived. An analysis of another in-service blade with a thermal barrier coating is carried out. The aluminum content decreases below the bond coat surface due to Al diffusion caused by the Al-oxide formation. This results in the formation of an Al-decreased layer (ADL) along the leading and trailing edges. The ADL is not observed at the center of the blade chord. The specimens are extracted from the portions of the blade that are devoid of ADL, and they are subjected to a high temperature in air. On the basis of the increase in the ADL thickness, a temperature-estimation equation is derived.

Convection-Diffusion Layer in an “Open Space” for Local Surface Treatment and Microfabrication using a Four-Aperture Microchemical Pen

ChemPhysChem ◽  
2017 ◽  
Vol 18 (17) ◽  
pp. 2357-2363 ◽  
Author(s):  
Sifeng Mao ◽  
Yong Zhang ◽  
Weifei Zhang ◽  
Hulie Zeng ◽  
Hizuru Nakajima ◽  
...  
Keyword(s):  
Surface Treatment ◽  
Diffusion Layer ◽  
Open Space ◽  
Local Surface ◽  
Convection Diffusion

scholarly journals Structure Formation of Hypereutectic Al-Si-Alloys Produced by Laser Surface Treatment

2014 ◽  
Vol 60 (6) ◽  
pp. 389-394 ◽  
Author(s):  
Sergey Nikolaevich Grigoriev ◽  
Tatyana Vasilievna Tarasova ◽  
Galina Olegovna Gvozdeva ◽  
Steffen Nowotny
Keyword(s):  
Surface Treatment ◽  
Structure Formation ◽  
Laser Surface ◽  
Laser Surface Treatment
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