scholarly journals DEVELOPMENT OF INNOVATIVE METHOD OF STEEL SURFACE HARDENING BY A COMBINED CHEMICAL-THERMAL TREATMENT

2016 ◽  
Vol 6 ◽  
pp. 46-52
Author(s):  
Kateryna Kostyk
Keyword(s):  
Thermal Treatment ◽  
Transition Zone ◽  
Diffusion Layer ◽  
Treatment Time ◽  
Combined Treatment ◽  
Surface Hardness ◽  
Boride Layer ◽  
Complex Chemical ◽  
The Matrix ◽  
Different Temperatures

The aim of the article is a hardening of the surface steel layers due to the combination treatment. Samples of steel 38Cr2MoAl were hardened by complex chemical and thermal treatment such as carburizing and subsequent boriding. It was established that surface double-layer hardening for steel 38Cr2MoAl with sequential saturation with atomic carbon (during carburizing) and atomic boron (during furnace boriding) at different temperatures allowed to form a boride layer with transition zone. The obtaining transition zone can improve operational properties of machine parts and tools by micro-friability reduction of diffusion layer. An optimal mode of complex chemical-thermal treatment (CTT) was obtained for the regime, which includes carburizing at 950 °C for 2 hours, boriding at 950 °C for 2 hours, which allows to get the best value for the surface hardness of 22 GPa with a maximum overall diffusion layer 1.4 mm. Due to the technology of combined treatment we can significantly reduce treatment time compared to traditional hardening means and significantly improve product performance properties due to the transition zone between the borides and the matrix of machine elements. The technology can be used in enterprises where there is any hardening furnace without additional installation or conversion of equipment.

Effects of Thermal Treatment on the Structure of Eu:YAG Nanopowder

2007 ◽  
Vol 128 ◽  
pp. 107-114 ◽  
Author(s):  
Maria Luisa Saladino ◽  
Eugenio Caponetti ◽  
Stefano Enzo
Keyword(s):  
Thermal Treatment ◽  
Lattice Strain ◽  
Rietveld Method ◽  
Lattice Parameter ◽  
Spherical Particles ◽  
X Rays ◽  
Garnet Phase ◽  
The Matrix ◽  
Different Temperatures ◽  
Co Precipitation

Eu:YAG nanopowder precursors were obtained by co-precipitation of aluminium, yttrium and europium nitrates solution with ammonia. The hydroxides precursors were calcined at different temperatures from 900 to 1200°C as a function of holding time (1, 2 and 6 hours). The presence of Eu3+ ions in the matrix was confirmed by Energy Dispersive X-rays analysis. X-Ray Diffraction investigation by the Rietveld method shows that the sample treated at 900°C for 1 hour is essentially the garnet phase with the minor presence of hexagonal and monoclinic metastable phases. The Eu3+ ions are incorporated into the garnet phase, as is suggested by the lattice parameter value being larger than that in literature data (homogeneous strain). For the sample treated at 900°C for 1 hour, electron microscopy observations showed agglomerates of spherical particles of mean size about 50 nm. At higher temperature treatments and for longer holding times the minority hexagonal and monoclinic phases totally disappeared. However, the lattice parameters of the cubic garnet phase gradually decreased with temperature, suggesting an expulsion of Eu3+ ions from the solid solution. Simultaneous with this, it was noted that the lattice strain reached a maximum value, but to later decrease, due to the vacancies created by the Eu species initially migrating to the surface of the coherent domains of diffraction. The lattice strain definitely decreased upon more drastic thermal treatments. Meanwhile, FEG-SEM and TEM observations on the same samples confirmed the growth of the garnet particles as a function of the thermal treatment.

Enhanced Surface Hardness by Boron Diffusion in Martensitic Stainless Steel via Cathodic Reduction and Thermal Diffusion Based Boriding (CRTD-Bor)

2015 ◽  
Vol 719-720 ◽  
pp. 25-28 ◽  
Author(s):  
G. Kartal Sireli ◽  
C. Yelkarasi ◽  
P. Ozkalafat ◽  
S. Timur ◽  
M. Urgen
Keyword(s):  
Thermal Diffusion ◽  
Single Phase ◽  
Surface Hardness ◽  
Boride Layer ◽  
Cathodic Reduction ◽  
Boron Diffusion ◽  
Cross Sectional ◽  
The Matrix ◽  
Enhanced Surface ◽  
Borided Steel

In this study, a developed new boriding method called as “Cathodic Reduction and Thermal Diffusion based Boriding” (CRTD-Bor) was applied to increase the surface hardness of 400 series steels. The cross-sectional examination of borided steel revealed that the boride layers consisted of single phase Fe2B. A dense and continuously 25μm thick Fe2B layer could be formed after 20 minutes of CRTD-Bor. The grown boride layer exhibited 1500±200 HV on top, and gradually decreased to the matrix (325 ± 25 HV).

scholarly journals Increasing the Surface Hardness of Cast Iron by Electrodeposition of Borides in Molten Salts

2017 ◽  
Vol 62 (2) ◽  
pp. 1015-1018 ◽  
Author(s):  
A.H. Al-Azzawi ◽  
J. Sytchev ◽  
P. Baumli
Keyword(s):  
Cast Iron ◽  
Current Density ◽  
Boron Content ◽  
Surface Hardness ◽  
High Hardness ◽  
Boride Layer ◽  
Electrochemical Process ◽  
Different Temperatures ◽  
Hardness Values ◽  
Very High

AbstractIn this paper the electrodeposition of boron on the surface of cast iron as a coating is applied to increase the hardness and protect the substrate against abrasive wear. The boron containing coating was synthesized by electrodeposition process from a NaCl-KCl (1:1 mol)-10 w%NaF-10w% KBF4molten salt. The effect of electrolysis parameters (temperature and time) on the hardness is presented; the current density varied in the range −37 – −4.5 mA/cm2, allowing perfect coverage of and respect for dimensions. The electrochemical process was carried out at different temperatures (750°C-900°C) and for different periods of time (5-10 hours). Depending on the current density and duration of electrolysis, the deposits consist of FeB or Fe2B. Microhardness measurements across the boride layer indicated very high hardness values (between 1600 and 2100 HV0.05). The structure of the boride layer is linked to its boron content and thermal history: as-deposited coatings present very small grain sizes and can be considered as nearly amorphous.

scholarly journals Effect of Humidity-Controlled Dehydration on Microbial Growth and Quality Characteristics of Fresh Wet Noodles

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 844
Author(s):  
Jun-Jie Xing ◽  
Dong-Hui Jiang ◽  
Zhen Yang ◽  
Xiao-Na Guo ◽  
Ke-Xue Zhu
Keyword(s):  
Shelf Life ◽  
Microbial Growth ◽  
Treatment Time ◽  
Positive Influence ◽  
Quality Characteristics ◽  
Plate Count ◽  
Cooking Properties ◽  
Total Plate Count ◽  
Different Temperatures

Humidity-controlled dehydration (HCD) was innovatively applied in this paper to control the growth of microorganisms in fresh wet noodles (FWN). Effects of HCD treatment with different temperatures (40, 60 or 80 °C), relative humidity (RH, 50%, 70% or 90%) and treatment time (5–32 min) on the total plate count (TPC), the shelf-life, and qualities of FWN were investigated. The results showed that HCD reduced the initial microbial load on the fresh noodles and extended the shelf-life up to 14–15 days under refrigeration temperature (10 °C). A 1.39 log10 CFU/g reduction for the initial TPC was achieved after HCD treatment at the temperature of 60 °C and RH of 90%. HCD with higher RH had a more positive influence on quality improvement. The L* values, the apparent stickiness, and the cooking properties of the noodle body were improved by HCD while good sensory and texture quality of noodles were still maintained after the dehydration process.

Effect of temperature on composite films made with activated carbon, graphite, or graphene oxide (GO) in a gelatin matrix

BioResources ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 77-95
Author(s):  
Siqiao Yang ◽  
Haichao Li
Keyword(s):  
Contact Angle ◽  
Activated Carbon ◽  
Water Absorption ◽  
Composite Films ◽  
Effect Of Temperature ◽  
Gelatin Matrix ◽  
Vapour Permeability ◽  
Blending Method ◽  
The Matrix ◽  
Different Temperatures

Activated carbon, graphite, and GO/gelatin composite films were prepared by the blending method. The properties of composites were characterized by tensile strength (TS), elongation at break (EB), water vapour permeability (WVP), water-absorption ability, contact angle, scanning electron microscopy (SEM), and moisture at different temperatures. The properties of GO/gelatin composite films were better when each of three kinds of carbon materials were used as reinforcement phases and added into the matrix gelatin. The results showed that EB and TS of GO/gelatin composite films were both excellent. The moisture of GO/gelatin composite films was greater than the others. SEM micrographs showed that GO had better compatibility and dispersibility with gelatin than activated carbon and graphite. The water absorption of GO/gelatin composite films were low, at 15 °C and 25 °C, and the WVP was low at 35 °C. The WVP of GO/gelatin composite films was lower than the others at different temperatures. The contact angle of GO/gelatin composite films was larger than the others.

Increasing Hardness of Surface Layer of Low-Carbon Steel by Account of Plasma Treatment of Coating Modification

2021 ◽  
Vol 316 ◽  
pp. 794-802
Author(s):  
Andrey E. Balanovsky ◽  
Van Trieu Nguyen
Keyword(s):  
Surface Layer ◽  
Thermal Treatment ◽  
Plasma Treatment ◽  
Plasma Heating ◽  
High Surface ◽  
Surface Hardness ◽  
High Hardness ◽  
Diffusion Region ◽  
Low Carbon ◽  
Wide Range

The Purpose of paper is to conduct studies to assess the possibility of increasing the hardness of the surface layer of steel St3 grade by plasma heating of the applied surface coating containing powder alloy PR-N80X13S2R. Mixtures of pasta were divided into 2 groups: for furnace chemical-thermal treatment and plasma surface melting. The study of the microstructure showed a difference in the depth of the saturated layer, depending on the processing method, during chemical-thermal treatment-1 mm, plasma fusion - 2 mm. The results of measuring the surface micro-hardness showed that, the obtained coating from a mixture of PR-N80X13S2R + Cr2O3 + NH4Cl has a uniform high surface hardness (31-64 HRC), from a mixture of only PR-N80X13S2R - the surface hardness varies in a wide range (15-60 HRC). The study of the microhardness of the cross section of the surface layer showed that, the diffusion region: from a mixture of powder PR-N80X13S2R + Cr2O3 + NH4Cl has uniform hardness (450-490 HV); from a mixture of PR-N80X13S2R - hardness increases in the depth of the molten region (from 300 to 600 HV), and sharply decreases in the heat affected zone (210-170 HV). The use of PR-N80X13S2R alloy powder as the main component in the composition of the paste deposited on the St3 surface during plasma treatment leads to the formation of a doped surface layer with high hardness.

Effect of Heat-Treatment Time on Microstructure and Mechanical Properties of Mg-5Gd-2Y-2Zn-0.5Zr Alloy

2012 ◽  
Vol 482-484 ◽  
pp. 1384-1389 ◽  
Author(s):  
Ling Gang Meng ◽  
Can Feng Fang ◽  
Peng Peng ◽  
Nai Pu Li ◽  
Qiong Zhu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Treatment Time ◽  
Time Range ◽  
Lpso Phase ◽  
High Temperature Heat Treatment ◽  
Lpso Structure ◽  
The Matrix ◽  
New Type ◽  
The Stability

Microstructure evolution of Mg-5Gd-2Y-2Zn-0.5Zr alloy during high temperature heat-treatment at 500°C in the time range 10-70h was investigated. The results show that after adding the element Y, the as-cast Mg-5Gd-2Y-2Zn-0.5Zr alloy forms the Mg12Zn(Y,Gd) phase with 18R-LPSO structure at the grain boundary. During heat-treatment at 500°C, the stability of 18R-LPSO structure is weakened by Gd atoms, parts of LPSO phases dissolve gradually into the matrix with time prolonged and a new type Mg(Y,Gd)Zn phase come into being. LPSO phase in the grain boundary can ensure the ultimate tensile strength and elongation of the alloy, and effect of dissevering on the LPSO phase by Mg(Gd,Y)Zn phase results the decrease of UTS and elongation.

The Reactivity of CaTi4(PO4)6 with Alumina and Y-TZP Ceramics

2007 ◽  
Vol 361-363 ◽  
pp. 787-790
Author(s):  
Sabina Beranič Klopčič ◽  
Irena Pribošič ◽  
Tomaž Kosmač ◽  
Ute Ploska ◽  
Georg Berger
Keyword(s):  
Room Temperature ◽  
Xrd Analysis ◽  
Second Phase ◽  
Reaction Products ◽  
Stabilized Zirconia ◽  
Monoclinic Zro2 ◽  
Commercial Alumina ◽  
The Matrix ◽  
Different Temperatures ◽  
Edx Analyses

The reactivity of CaTi4(PO4)6 (CTP) with alumina and yttria-stabilized zirconia (Y-TZP) ceramics was studied. CTP powder was synthesized and composites with commercial alumina or zirconia matrices containing 10 wt% of CTP were prepared. They were sintered at different temperatures and characterized using XRD, SEM, and EDX analyses. The results showed that the alumina/CTP and Y-TZP/CTP composites start to react below 1000 °C. In the alumina/CTP composite the first reaction product, detected at 970 °C, was AlPO4. At temperatures above 1280 °C TiO2 and CaTiO3 were also formed and no CTP peaks could be detected using XRD analysis. The composite sintered at 1500 °C consisted of Al2O3 matrix, AlPO4, TiO2, CaTiO3 and Al2TiO5. The reaction products formed in the Y-TZP/CTP composite at 970 °C were TiO2 and Ca2Zr7O16. At higher sintering temperatures, 1280 °C and above, CTP was no longer present, Ca2Zr7O16 decomposed, forming CaO2 and ZrO2, and Y2O3 was consumed to form YPO4. Consequently, upon cooling to room temperature the matrix phase transformed to monoclinic ZrO2. Based on these results it can be concluded that CTP is not a suitable bioactive second phase for the fabrication of CTP composites with alumina or zirconia matrices.

Incorporation of Magnetite in Toughened PLA Nanocomposite: Tensile and Thermal Stability

2022 ◽  
Vol 1048 ◽  
pp. 15-20
Author(s):  
Ruey Shan Chen ◽  
Sahrim Ahmad
Keyword(s):  
Thermal Stability ◽  
Tensile Testing ◽  
Treatment Time ◽  
Optimum Distribution ◽  
Melt Compounding ◽  
The Matrix ◽  
Liquid Natural Rubber ◽  
Suitable Treatment ◽  
Ultrasonication Time ◽  
Internal Mixer

In this study, liquid natural rubber (LNR) toughened polylactic acid (PLA) incorporated with magnetite (Fe3O4) nanocomposites were fabricated via melt-compounding in an internal mixer and followed by hot/cold pressing. The effects of ultrasonic treatment time (1-3 hours) and Fe3O4 (0.5-4.0 wt%) nanoparticles loading on tensile, morphology and thermal stability were investigated. Based on tensile testing results, the ultrasonication time of 1 hour was served as the most suitable treatment period to achieve the optimum distribution of Fe3O4 within PLA/LNR matrix. Among the investigated nanoparticles loading, 1 wt% Fe3O4 nanocomposite presented the highest tensile strength of 23.7 MPa, Young’s modulus of 1293.5 MPa and strain at break of 2.8%. SEM micrographs showed that the over-treated nanocomposites with 2-3 hours and over-high nanoparticles loading had resulted in the formation of clusters in the matrix. With increasing Fe3O4 loading, the decomposition of PLA/LNR nanocomposites was initiated earlier.

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