Mechanism of thermochemical growth of iron borides on iron

Martini, Carla; Palombarini, G.; Carbucicchio, M.

doi:10.1023/b:jmsc.0000012924.74578.87

Cited by 156 publications

(84 citation statements)

References 8 publications

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“…The copper alloyed ductile cast iron sample showed only the Fe 2 B phase, composed of 8.83% boron, with a centered body tetragonal arrangement, a modulus of elasticity between 285 and 295 GPa and density of 7.43 g/cm 3 . However, the substrates of ductile cast iron alloyed with copper-nickel or copper-nickelmolybdenum also showed the FeB phase, rich in boron (16.3% by weight), orthorhombic crystal structure, elastic modulus of 590 GPa and density of 6.75 g/cm 39, 10,21 . The FeB phase presents a higher hardness but lower toughness, and its formation occurs under tensile stresses (contrary to Fe 2 B formation that occurs under compressive stresses) what commonly give rise to cracks that propagate at its interface [22][23][24][25] .…”

Section: Resultsmentioning

confidence: 99%

Boro-Austempering Treatment of Ductile Cast Irons

et al. 2018

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Samples of ductile cast irons alloyed with Cu, Cu-Ni and Cu-Ni-Mo were austempered, borided and boro-austempered and characterized for hardness and micro-adhesive wear behavior. The kinetics of layer formation was also studied. The boriding method used was molten borax bath, in periods of 2 and 4 hours at temperatures of 850, 900 and 950 ºC. The direct austempering treatment was performed immediately following the boriding treatment (from 850, 900 and 950 ºC) using molten salt baths at temperatures of 240, 300 and 360 ºC for 4 hours (boro-austempering treatment). For comparative purposes, the conventional austempering treatment was also conducted. Optical microscopy, scanning electron microscopy, Brinell hardness measurements (on the substrate) and Vickers (on the layers) were performed, along with micro-adhesive wear tests. The boriding treatment resulted in the formation of high hardness layers, in the range of 1450 to 1750 HV, with high wear resistance. The wear resistance of borided and boro-austempered samples were increased by 40 times when compared to as cast or austempered samples, indicating the high efficiency of this type of treatment in increasing the wear resistance of this material.

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Section: Resultsmentioning

confidence: 99%

Boro-Austempering Treatment of Ductile Cast Irons

et al. 2018

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“…The patterns of X-ray diffraction (Figure 3) show the presence of FeB and Fe 2 B phases which are well compacted. However, Figure 2c) shows a mixture of phases; the FeB phase is defined as a FeB-base phase since it generally contains high boron products disolved therein because it grows from the transformation of the Fe2B phase 19 .…”

Section: Boriding Processmentioning

confidence: 99%

Damage Mechanisms in AISI 304 Borided Steel: Scratch and Daimler-Benz Adhesion Tests

et al. 2015

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In this study, damage mechanisms in the FeB/Fe 2 B coatings formed on the surface of AISI 304 steel are determined by adhesion tests. First, the boriding of the AISI 304 steel was carried out through the powder-pack method at 1223 K in the range from 2-10 h of exposure time. After treatment, Berkovich depth-sensing indentation test were conducted; the result showed tensil and compressive residual stresses in the FeB and Fe 2 B, respectively. The adhesion of borided steels was evaluated by the Daimler-Benz Rockwell-C and scratch test. Based on the scratch tracks, the chipping was the predominant mechanism at 2 and 6 h, with critical loads of 35 and 43 N, respectively; while spalliation was determined at 27 N for 10 h. Also, hertzian and tensil cracks, buckling and compressive delamination were determined in the AISI 304 borided steel by scanning electron microscope.

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“…3b). The acicular type of layer microstructure is related to the preferred orientation of boron diffusion in (002) crystallographic direction [32]. This type of layer growth is typically observed for low alloy steels [3,33].…”

Section: Microstructure and Phase Constitution Of Boride Coatingsmentioning

confidence: 94%

Oxidation stability of boride coatings

Ptačinová¹,

Drienovský²,

Palcut³

et al. 2016

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In this work, plain, low carbon steel S235JRG1 was boronized at 1273 K for 45-150 min by using a Durborid powder. The microstructure, phase constitution and oxidation behavior of the resulting boride layers have been investigated. Layers with an average thickness of 76-123 µm have been produced. The boride layer has a distinct tooth-like microstructure. It is composed of Fe2B and FeB in unequal amounts. The boride layer oxidation behavior has been investigated by a simultaneous thermal analysis in a flowing synthetic air at 873-1173 K for 21-24 h. A parabolic oxidation of the boride layer has been observed. The rate constants are found between 1.039 × 10 −9 to 3.781 × 10 −6 kg 2 m −4 s −1 , depending on temperature and oxidation time. The activation energy of oxidation at temperatures below 1173 K has been estimated to be 93 kJ mol −1 . At 1173 K, two successive parabolic periods have been found, followed by a breakaway oxidation behavior. The oxide scale of the boronized steel is composed of different iron oxides and iron borates. The oxidation mechanisms of boride coatings are discussed and implications towards high temperature stability are provided.K e y w o r d s : boronizing, high temperature oxidation, X-ray diffraction, thermogravimetric analysis

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Mechanism of thermochemical growth of iron borides on iron

Cited by 156 publications

References 8 publications

Boro-Austempering Treatment of Ductile Cast Irons

Boro-Austempering Treatment of Ductile Cast Irons

Damage Mechanisms in AISI 304 Borided Steel: Scratch and Daimler-Benz Adhesion Tests

Oxidation stability of boride coatings

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