Characterization of boride coatings on a ductile cast iron (original) (raw)
Related papers
Evaluation of Boride Layers on C70W2 Steel Using a New Approach to Characterization of Boride Layers
Materials
In this study, boride layers on C70W2 steel, obtained by boronizing at temperatures ranging from 870 to 970 °C and durations from 4 to 8 h, were investigated. The characterization of the layers was carried out using a new approach based on the change in the volume fraction of the boride phase. Analysis of the change in volume fraction showed that an increase in temperature and duration resulted in thicker layers, with temperature having a greater influence. Based on the volume fraction of the boride phase, the layer is divided into compact and toothed parts. With increasing temperature, the thicknesses of both parts of the layer increased. The thickness of the toothed part was the highest after 6 h of boronizing and further prolongation of boronizing led to a decrease in the thickness. Regression equations were estimated for the prediction of the volume fraction of the boride phase, the thickness of the compact part, and that of the toothed part of the boride layer as a function of ...
Characterization of Boride Layers on Ryalloy Steel
Metal ..., 2022
Boronizing is a thermochemical process in which the boron atoms are introduced into the steel surfaces. During this process, the boride layers with high hardness, wear-and corrosion-resistance are formed. In this study, the Royalloy (0.05 wt.% C; 12.6 wt.% Cr; 0.4 wt.% Si and 1.2 wt.% Mn) steel was powder-boronized at 900, 950, 975, 1000 or 1050 °C, and for 1, 3, 5, 7 or 10 h. The boronized samples were analyzed by X-ray diffraction analysis (XRD) to analyze their phase composition, and by scanning electron microscope to analyze their thickness and morphology at the interface with the substrate. To investigate the chemical elements redistribution during the boronizing process, the EDS mapping and EDS point analysis were used. The treatments produced boride layers with a thickness from 8 to 168 µm, depending on the boronizing parameters. During the boronizing process, the chromium was redistributed between the boride layers, where creates the chromium borides, and the transient region underneath the boride layers, where creates the particles with the biggest amount of chromium. The silicon was focused at the layersubstrate interfaces. The concentration of manganese was slightly higher in substrate compared to the boride layers.
Characterizations and Kinetic Modelling of Boride Layers on Bohler K190 Steel
In this study, the Bohler K 190 steel was used. The steel was manufactured by the powder metallurgy (PM) process. The boronizing process was carried out in the range of 1173 to 1323 K, for 1-10 h. The samples were boronized in solid medium, called the Durborid powder mixture. For the microstructural observations, the scanning electron microscopy was utilized for determining the morphology of interfaces and measuring the layers’ thicknesses. The phase composition of boride layers was also determined with X-ray diffraction analysis. To investigate the redistribution of chemical elements redistribution during the boronizing process, the EDS mapping and EDS point analysis were used. The boride layers were constituted by FeB and Fe2B phases except for 1173 K for 1 h. The values of Vickers microhardness of Fe2B, FeB and transition zone were estimated. Finally, to assess the boron activation energies in FeB and Fe2B, the so-called integral method was applied and the results in terms of act...
Aceh International Journal of Science and Technology, 2012
- The property such as microhardness of boride layer formed on S45C iron was investigated. Boronizing was carried out in a solid medium consisting of nano size powders of 50% B4C as a donor, 45% SiC as a diluent, and 5% KBF4 as an activator treated at the temperature of 10000C for 8 hours. The phases that were formed on the substrate was found as Fe2B and FeB layer that had smooth and flate shape morphology. The hardness of boride layer on S45C was over 2000 HV, while the hardness of untreated S45C iron was about 196,39 HV. Depending on process time and temperature, the depth of boride layer ranges from 25 to 55 μm, leading to a diffusion controlled process. Keywords : Boronization, hard layer, heat treatment, B4C.KBF4.SiC powder, low carbon steel.
Production and characterization of boride layers on AISI D2 tool steel
Vacuum, 2010
a b s t r a c t AISI D2 is the most commonly used cold-work tool steel of its grade. It offers high hardenability, low distortion after quenching, high resistance to softening and good wear resistance. The use of appropriate hard coatings on this steel can further improve its wear resistance. Boronizing is a surface treatment of Boron diffusion into the substrate. In this work boride layers were formed on AISI D2 steel using borax baths containing iron-titanium and aluminium, at 800 C and 1000 C during 4 h. The borided treated steel was characterized by optical microscopy, Vickers microhardness, X-ray diffraction (XRD) and glow discharge optical spectroscopy (GDOS) to verify the effect of the bath compositions and treatment temperatures in the layer formation. Depending on the bath composition, Fe 2 B or FeB was the predominant phase in the boride layers. The layers exhibited ''saw-tooth'' morphology at the substrate interface; layer thicknesses varied from 60 to 120 mm, and hardness in the range of 1596-1744 HV were obtained.
An approach to kinetic study of borided steels
Surface & Coatings Technology, 2005
In present study, kinetic studies on borided AISI 5140, AISI 4340 and AISI D2 steels are reported. Steels were borided in a salt bath consisting of borax, boric acid and ferro-silicon between 1073 and 1273 K for 2, 4, 6 and 8 h. The morphology and types of borides formed on the surface of steel substrates were confirmed by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Boride layer thickness formed on the borided steels ranged from 21 to 238 Am depending on process temperature, treatment time and alloying elements of the substrates. The hardness of borides formed on the samples changes between 1077 and 2140 HV 0.1 according to treatment time and temperature. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe 2 B sublayers as a function of boronizing time and temperature in the range of 1123 -1273 K. The depth of the tips of the most deeply penetrated FeB and Fe 2 B needles are taken as measures for diffusion in the growth directions. The kinetics of the reaction, K = K o exp ( À Q/RT), have also been determined by varying the boriding temperature and time. The results showed that K increase with boriding temperature. Activation energies ( Q) of borided AISI 5140, AISI 4340 and AISI D2 steels at present study were determined as 223, 234 and 170 kJ/mol, respectively. Moreover, an attempt was made to investigate the possibility of predicting the contour diagrams of boride layers variation and to establish some empirical relationships between process parameters and boride layer thicknesses. D
Growth kinetics of the boride layers formed on SAE 1035 steel
Matériaux & Techniques, 2013
Growth kinetics of the boride layers formed on SAE 1035 steel has been investigated during the boriding treatment. This treatment was carried out in slurry salt bath consisting of borax, boric acid and ferrosilicon for temperatures ranging from 1073 to 1273 K and treatment times of 2, 4 and 8 h. The presence of both FeB and Fe2B phases formed on the surface of SAE 1035 steel was confirmed by X-ray diffraction. Scanning electron microscopy (SEM) and optical microscopy examinations showed that the boride layers have a saw-tooth morphology. The thickness of boride layers was found to be increased when the treatment time and the boriding temperature increase, its value ranged from 20 to 387 µm. The average hardness of the boride layer was about 1760 ± 200 HV0.1, while the hardness of un-borided steel was about 225 ± 20 HV0.1. The fracture toughness of boride layers (KC) was found to be ranged between 3.42 and 4.57 MPa m 1/2. The kinetic study showed a parabolic relationship between the boride layer thickness and the process time. The value of boron activation energy for the borided SAE 1035 steel was estimated as 227.51 kJ mol −1 .
Applied Surface Science, 2006
Through this work we study the influence of the thickness of boron paste in the growth of Fe 2 B boride layer during the paste boriding thermochemical treatment applied on AISI 1045 steel. Different thickness of boron paste over the material surface with constant temperature and time show the variability of the diffusion coefficient of boron in Fe 2 B phase depending, basically, on the boron potential at the external surface of the substrate. The mobility of boron in the formed phase is determined by the balance mass equation that considers the concentration profiles in the corresponding interphases layer-substrate, the thermodynamic equilibrium in the growth of the iron boride layer and the experimental results obtained during the process. #
Coatings
Boride layers are typically used to combat the wear and corrosion of metals. For this reason, to improve our knowledge of the boriding process, this research studied the effect of the size of the treated material on the kinetics of the growth of the boride layers obtained during a solid diffusion process. The purpose was to elucidate how the layers’ growth kinetics could be affected by the size of the samples since, as the amount of matter increases, the amount of energy necessary to make the process occur also increases. Furthermore, the level of activation energy seems to change as a function of the sample size, although it is considered an intrinsic parameter of each material. Six cylindrical samples with different diameters were exposed to the boriding process for three different exposure times (1.5, 3, and 5 h). The treatment temperatures used were 900, 950, and 1000 °C for each size and duration of treatment. The results show that the layer thickness increased not only as a fu...
Boride Layer Growth Kinetics of Aisi H13 Steel Borided with Nano-Sized Powders
2018
Growth kinetics of boride layers in AISI H13 steel was investigated using the pack boriding method at temperatures of 1073, 1173 and 1273 K (800°C, 900°C and 1000°C) for periods of 2, 4 and 6 h with nano-sized boron (NB) and micron-sized Ekabor II powders as boriding agents. The total thickness of the boride layer (including both FeB and Fe2B) after boriding at 1273 K (1000°C) for 6 h was 103.8 μm and 96.5 μm for the NB and Ekabor II specimens, respectively. X-ray diffraction analysis of the boride layers on the surfaces borided with NB and Ekabor II revealed the presence of FeB and Fe2B phases with sawtooth morphology. The FeB/Fe2B volume ratio was higher in the specimens borided with NB. The thickness of the boride layer (FeB + Fe2B) increased with the increasing boriding temperature and time. The FeB layer in the NB specimen displayed a (002) preferred orientation.