Multi-component boron coatings on low carbon steel AISI 1018

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16 2.4 Characteristics and Properties of Boride Layer The prominent saw-tooth structure of the boride layer is well observed in pure iron, unalloyed low-carbon steel, and low alloy steels. When the alloying elements and/or carbon contents in the substrate steel are increased, the thickness of the boride layer is decreased. In addition, the smooth interface can also be observed instead of the saw-tooth structure, as illustrated in Figures 2.2 and 2.3. Alloying elements, except nickel, cobalt, and manganese, which delay the <strong>boron</strong> diffusion into the substrate, can increase the proportion of FeB constitution [4]. For example, in <strong>boron</strong>ized stainless steel, alloying elements causes the thin smooth interface of almost 100% FeB phase of the boride layer. Figure 2.2 The effect of steel composition on the morphology and thickness of the boride layer.
17 Proportion of alloying elements, at.% Figure 2.3 The effect of percent alloying elements on the boride layer thickness [7]. 2.4.1 Effects of Alloying Elements in Boronizing Processes Carbon, Silicon, and Aluminum is insoluble in the boride layer. During <strong>boron</strong>izing, the boride layer expels carbon and silicon from the surface into the substrate matrix, and forms the precipitation of iron silicoboride (FeSi 0. 4B 0.6 or FeSiB 2) and iron carboboride (Fe23(B,C)6 and Fe 3(B,C) beneath and/or between the boride saw-teeth structure. The contents of silicon and aluminum (larger than 0.8%) underneath the boride layer can form a soft ferrite phase, which has a low load-carrying capacity [I1]. Under the high surface pressure, the failure can occur due to the hard boride layer penetrating into this soft ferrite region. Nickel will restrict the solubility of <strong>boron</strong> atoms in iron because it diffuses into the boride layer and precipitates Ni 3B from the boride layer at the Fe2B/substrate interface. The results are the reduction of boride-layer thickness and the saw-tooth structure. Although nickel may slightly reduce the microhardness value of the boride layer, nickel helps impeding the formation of FeB [II] .
Page 1 and 2: Copyright Warning & Restrictions Th
Page 3 and 4: ABSTRACT MULTI-COMPONENT BORON COAT
Page 5 and 6: MULTI-COMPONENT BORON COATINGS ON L
Page 7 and 8: APPROVAL PAGE MULTI-COMPONENT BORON
Page 9 and 10: Roumiana S. Petrova, Naruemon Suwat
Page 11 and 12: vii
Page 13 and 14: TABLE OF CONTENTS Chapter Page 1 IN
Page 15 and 16: TABLE OF CONTENTS (Continued) Chapt
Page 17 and 18: TABLE OF CONTENTS (Continued) Chapt
Page 19 and 20: LIST OF TABLES Table Page 2.1 The M
Page 21 and 22: LIST OF FIGURES (Continued) Figure
Page 27 and 28: CHAPTER 1 INTRODUCTION 1.1 Objectiv
Page 29 and 30: 3 borosiliconizing using bo
Page 31 and 32: 5 During boronizin
Page 33 and 34: 7 the FeB/Fe2B interface. Such crac
Page 35 and 36: 9 nickel metal do not show the stro
Page 37 and 38: 11 2.3.2 Paste Boronizing The paste
Page 39 and 40: 13 2.3.5 Plasma Boronizing The plas
Page 41: 15 Table 2.2 The Multi</str
Page 45 and 46: 19 when boronizing
Page 47 and 48: 21 in the process of powder pack <s
Page 49 and 50: 23 Torun [46] studied the b
Page 51 and 52: 25 10 3 Figure 2.4 The effect of st
Page 53 and 54: 27 • The surface hardness of <str
Page 55 and 56: 29 Figure 2.7 The hardness value fo
Page 57 and 58: 31 2.7 Research and Development on
Page 59 and 60: 33 Instead of toxic borane and <str
Page 61 and 62: 35 Tsipas et al. [76] utilized the
Page 63 and 64: 37 Buijnsters et al. [85] investiga
Page 65 and 66: 39 in terms of thickness and microh
Page 67 and 68: 41 these boride layers reduced the
Page 69 and 70: 43 The decorative boride co
Page 71 and 72: CHAPTER 3 MULTI-COMPONENT BORONIZIN
Page 73 and 74: 47 3.2.2 Procedures of Boronizing H
Page 75 and 76: 49 Specimen Sample Preparation proc
Page 77 and 78: 51 View direction through a microsc
Page 79 and 80: 53 thicknesses was shown as a histo
Page 81 and 82: 55 the test force, gf the length of
Page 83 and 84: 57 3.3.4 Corrosion Resistance Testi
Page 85 and 86: 59 2. Quantitative Phase Analysis Q
Page 87 and 88: 61 B. The variance of the crystalli
Page 89 and 90: 63 SDI Application software was use
Page 91 and 92: 65 The Intensity /k can be refined
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67 The profile value: The weighted
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69 In Figure 4.1 b), the coating im
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71 4.1.2 Phase Identification The X
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73 Table 4.1 The Lattice Parameters
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75 4.1.4 Corrosion Resistance The c
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77 4.2 Boron- Chromium - Iron (B -
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83 4.2.4 Mierohardness In B-Cr-Fe s
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85 4.2.6 Oxidation Resistance The h
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Figure 4.13 The morphology images o
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Figure 4.14 The XRD pattern (refine
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91 Figure 4.15 The microdiffraction
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93 4.3.5 Corrosion Resistance The c
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95 4.4 Boron — Tungsten - Iron (B
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Figure 4.23 The mierofluoreseence o
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103 4.4.5 Corrosion Resistance The
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105 4.5 Boron — Niobium - Iron (B
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107 4.5.2 Phase Identification The
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109 Table 4.5 The Lattice Parameter
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M 11 4.5.4 Microhardness In B-Nb-Fe
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113 4.5.6 Oxidation Resistance The
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Figure 4.34 The morphology images o
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Figure 4.35 The XRD pattern (refine
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1119 Figure 4.36 The microdiffracti
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123 4.7 Boron — Titanium - Iron (
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131 4.8 Boron — Zirconium - Iron
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139 4.9 Boron — Hafnium - Iron (B
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g 145 4.9.5 Oxidation Resistance Th
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147 5.1.1 Microstructure of B-Cr-Fe
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149 As mention above, the coating t
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151 Atomic size: 1.241A Crystal str
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153 Coating thickne, (Mean): 84.24
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155 Due to the atomic size, substit
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157 5.3 Microhardness In bo
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159 5.4 Corrosion Resistance In thi
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161 5.5 Oxidation Resistance In one
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Figure 5.7 The comparison of oxidat
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165 For transition metals Group IVB
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APPENDIX A PHASE DIAGRAMS The binar
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Figure A.3 Phase diagrams in B-Mo-F
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Figure A.5 Phase diagrams in B-Nb-F
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Figure A.7 Phase diagrams in B-Ti-F
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Figure A.9 Phase diagrams in B-Hf-F
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177 Name and formula Reference code
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Name and formula Reference code: 04
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195 15. Selçuka, B., Tpekb, R., Ka
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197 41. Ueda, N., Mizukoshi, T., De
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199 67. Davis, J. A., Wilbur, P. J.
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201 90. Uzunov, N., Ivanov, R. (200
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203 114. Jayaraman, S., Gerbi, J. E
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Multi-component boron coatings on low carbon steel AISI 1018

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