Boride Layer Research Articles

The importance of plasma paste boriding parameters for thickness, nanomechanical properties, residual stress distribution and fracture toughness of layers produced on Nimonic 80A-alloy

Borided layers of different thickness were produced on Nimonic 80A-alloy using plasma paste boriding method. The process was carried out at the temperature of 750 °C, 800 °C and 850 °C for 3 h and 6 h. All produced layers consisted of a fine-grained mixture of nickel borides and chromium borides. Higher boriding temperature and time resulted in the obtaining of boron-rich CrB phase in the microstructure of the borided layer. Simultaneously, this layer was characterized by higher hardness and Young’s modulus. Compressive residual stresses were generated in all produced layers. However, the most advantage course of the curve is characteristic of the borided layer produced at the highest temperature and time. The increase in layer thickness was accompanied by a decrease in the crack’s length (from 33.8 to 7.7 µm), as well as an increase in the fracture toughness (from 0.4439 to 2.4087 MPa·m1/2).

Comparative study on electrochemical corrosion behavior of boronized X52 steel in 1 M HCl and H2SO4 solutions

This paper investigates the effect of boronizing treatment on the corrosion resistance of API X52 steel. Borides were grown on API X52 steel in a powder mixture containing 5% B4C as a boron source, 5% NaBF4 as an activator, and 90% SiC as diluents for 4 hours at 950 °C. X-ray diffraction (XRD) analysis revealed that the sample's boride layer contains only Fe2B phases. The corrosion behavior of borided and unborided specimens was investigated using the Tafel extrapolation method in 1M HCl and H2SO4 solutions. The results show that borided specimens have better corrosion resistance than unboronized specimens. The formation of layers of protective iron borides reduces the corrodability of the steel in the borided specimens. Boronizing increased the corrosion resistances of X52 steel in HCl and H2SO4 by 23 and 77-fold, respectively.

Electronic structure, bonding characteristics, and mechanical behaviors of a new family of Si-containing damage-tolerant MAB phases M5SiB2 (M = IVB—VIB transition metals)

MAB phases are layered ternary compounds with alternative stacking of transition metal boride layers and group A element layers. Until now, most of the investigated MAB phases are concentrated on compounds with Al as the A element layers. In this work, the family of M5SiB2 (M = IVB—VIB transition metals) compounds with silicon as interlayers were investigated by density functional theory (DFT) methods as potential MAB phases for high-temperature applications. Starting from the known Mo5SiB2, the electronic structure, bonding characteristics, and mechanical behaviors were systematically investigated and discussed. Although the composition of M5SiB2 does not follow the general formula of experimentally reported (MB)2zAx(MB2)y (z = 1, 2; x = 1, 2; y = 0, 1, 2), their layered structure and anisotropic bonding characteristics are similar to other known MAB phases, which justifies their classification as new members of this material class. As a result of the higher bulk modulus and lower shear modulus, Mo5SiB2 has a Pugh’s ratio of 0.53, which is much lower than the common MAB phases. It was found that the stability and mechanical properties of M5SiB2 compounds depend on their valence electron concentrations (VECs), and an optimum VEC exists as the criteria for stability. The hypothesized Zr and Hf containing compounds, i.e., Zr5SiB2 and Hf5SiB2, which are more interesting in terms of high-temperature oxidation/ablation resistance, were found to be unfortunately unstable. To cope with this problem, a new stable solid solution (Zr0.6Mo0.4)5SiB2 was designed based on VEC tuning to demonstrate a promising approach for developing new MAB phases with desirable compositions.

Kinetics and Mechanical Characterization of Hard Layers Obtained by Boron Diffusion in 80/20 Nickel–Chromium Alloy

This study examines the formation of hard layers containing Ni-B and Cr-B on the surface of 80/20 nickel–chromium alloy. The work evaluates the mechanical properties of the boride layers using instrumented nanoindentation. In addition, the growth kinetics of the coatings were assessed by applying a kinetic model that relates the layer thickness with the experimental parameters of temperature and treatment time. First, the boride layers were achieved using the powder-pack boriding process in a conventional furnace. The treatment time was set at 2, 4, and 6 h at temperatures of 900, 950, and 975 °C, respectively. The microstructure of the layers was analyzed by X-ray diffraction. The thickness of the layers showed a closed correlation with the experimental parameters of time and temperature, and was established between 38.97 and 156.49 µm for 2 h to 900 °C and for 6 h to 975 °C, respectively. The hardness and Young’s modulus values agree with those presented in the literature for boriding nickel alloys, being in the range of 1.3 GPa on average and 240 to 270 GPa, respectively. The resulting layers exhibited a characteristic diffusion zone where the hardness values decrease gradually without the typical high hardness gradient observed on borided steels.

Estimation of the wear and corrosion synergism of borided Inconel 718 alloy immersed in a neutral aqueous solution

This work investigates the tribocorrosion properties of the nickel boride layer on an Inconel 718 superalloy immersed in a neutral solution of sodium sulfate and sodium chloride. The solution simulates the corrosive environment created by the combustion reaction of sodium, sulfur, and oxygen when Ni-based superalloys are used in turbine blades. A powder-pack boriding process was conducted at 950 °C for 6 h, obtaining a nickel boride layer thickness of around 50 μm on the surface of the superalloy; microstructural analysis revealed that the boride layer was composed of Ni4B3–Ni2B–Ni3B. Further, depth-sensing Vickers microindentation tests were performed to assess the ratios of H/E and H³/E2 on the nickel boride layer.Additionally, tribocorrosion tests were conducted with a reciprocating tribometer and a typical three-electrode electrochemical cell. The counterpart was a 4.8 mm diameter alumina ball that applied 20 N for a sliding distance of 100 m. According to the ASTM G119-09 procedure, the total material loss rate due to tribocorrosion (T), which includes mass loss rate due to wear (Wc) and corrosion (Cw), was estimated.The results revealed a wear-dominant regime for the Reference material (Inconel 718 superalloy), attributed to passive film removal and high contact pressure at the tribopair, which increases the volume loss rate. On the other hand, the nickel boride layer on the Inconel 718 superalloy displayed a wear-corrosion regime due to boride layer debris that increased the corroded area. Under these experimental conditions, the presence of the nickel boride layer on the Inconel 718 superalloy improved tribocorrosion resistance by approximately three times.

Study on Low-Damage Cutting of Alfalfa Stalks by Self-Sharpening Blades of Gradient Material with Carbon-Nitron-Boronized Heat-Treatment

The work aims to realize low-damage cutting of Alfalfa stalk. The self-sharpening blades of gradient material were prepared by 40 Cr steel, then heat-treating the flank surface by carbon-nitron-boronized with a rare elements catalysis technique. The biological characteristics of Alfalfa incision self-healing and regeneration process were analyzed in order to compare the cutting effects of different blades. After treatment with carbon-nitron-boronized with rare elements catalysis, the flank surface and tip point of blades were coated by boride layer and carbonitriding layer. The composition, microstructure and properties of the carbon-nitron-boronized layer demonstrated a gradient distribution state, and had good wear resistance. A kinetic model for the formation of the carbon-nitron-boronized layer was proposed. The initial stage of heat-treatment was mainly a carbonitriding process. When continuous and compact boride was formed on the surface, it was mainly boridized. The results of field experiment indicated that compared with the commercial blades, the self-sharpening blades have excellent properties as wear resistance and long service life. In addition, the cut damage caused by the self-sharpening blades was less, the self-healing and regeneration process of Alfalfa stalk was normal, and the regeneration duration was greatly shortened. The blades with carbon-nitron-boronized heat-treatment could form the self-sharpening characteristics, always maintaining the cutting sharpness, and realized the low-damage cutting of Alfalfa stalk.

Metallurgical properties of boride layers formed in pack boronized cementation steel

Abstract In the present study, cementation steel was exposed to boronizing process at 950 °C for 6, 8, and 10 h. Microstructural changes on the surface of the samples after boron operation were inspected by optical microscope, scanning electron microscope, energy-dispersive spectroscopy, X-ray diffraction, electron back-scatter diffraction, and elemental mapping analysis. In addition, surface roughness, microhardness, and boride layer thicknesses were measured. The boride layers deposited on the cementation steel consisted either single or double phases. The level of boride deposit of all samples was achieved from 90 to 156 μm. The boride layer created at 950 °C for 10 h involved the FeB and Fe2B. The boride layers had a much higher hardness value than the substrate material due to the presence of FeB and Fe2B.

Effect of Chemical Composition of Boriding Agent on the Optimization of Surface Hardness and Layer Thickness on AISI 8620 Steel by Solid and Liquid Boriding Processes

Abstract Surfaces of cam shafts made of AISI 8620 steels were hardened by boriding processes in both solid and liquid mediums. Various chemical agents were used to achieve boride layers on the surfaces of the cam shafts in these processes. It was aimed to examine effects of the chemical agents on microhardness and thickness of the boride layers obtained. It was concluded that a bath composition of 5% B4C-90% SiC-5% KBF4 was appropriate for the hardest and thickest boride layer achieved in the solid medium, and a composition of 70% Na2B4O7-30% B4C in the liquid medium.

Microstructure and some properties of powder-pack borided Ti–5Mo–5V–8Cr–3Al alloy with special attention to the microstructure at the interface TiB/substrate

The borided layer was prepared on the surface of the Ti–5Mo–5V–8Cr–3Al alloy by powder-pack boriding at 1000°C-10h. SEM, EPMA and TEM were used to investigate the effects of alloying elements (Al, V, Mo and Cr) on the growth of TiB whiskers in the borided Ti–5Mo–5V–8Cr–3Al alloy. Wear properties of borided Ti–5Mo–5V–8Cr–3Al alloy were investigated using dry reciprocating friction tests. SEM results show that the thickness of boride layer in Ti–5Mo–5V–8Cr–3Al alloy is thinner than that in the Cp-Ti. This is attributed to the enrichment of alloying elements especially V in TiB/substrate by TEM, which hinders the diffusion of B atoms, thus resulting in the short and thick TiB whiskers in Ti–5Mo–5V–8Cr–3Al alloy. Borided Ti–5Mo–5V–8Cr–3Al alloy has the better wear resistance than as-received alloy.

Effect of the boriding environment on the wear response of laser-clad AlCoCrFeNi high entropy alloy coatings

Laser-clad AlCrFeCoNi high entropy alloy (HEA) coatings, produced on the surface of AISI 316 L stainless steel, were pack-borided at 1000 °C for 4 h in open air, high-purity Ar and vacuum environments. The HEA, which had an initial hardness of 6.14 ± 2.06 GPa, formed a complex boride layer consisting of (CoFe)B2, (CrFe)B2 and Cr2Ni3B6 phases on its surface, with hardness ranging from 15.95 ± 0.7 to 20.15 ± 4.50 GPa as a result of the boriding process. While the greatest boride layer thickness was obtained in the sample borided in vacuum, the highest surface hardness was obtained in the sample borided in air. The borided coatings showed improved wear resistance and lower friction values compared to the untreated control samples, both at 25 °C and 650 °C. The borided coatings also showed reduced coefficients of friction at 650 °C. The wear losses at 650 °C significantly exceeded those at 25 °C.

Determination of fracture toughness of boride layers grown on Co1.21Cr1.82Fe1.44Mn1.32Ni1.12Al0.08B0.01 high entropy alloy by nanoindentation

Multiphase boride layers consisting of (CoFe)2B, (Fe0.4Mn0.6)B, Cr2Ni3B6 and (Cr0.4Mn0.6)B were formed on the surface of Co1.21Cr1.82Fe1.44Mn1.32Ni1.12Al0.08B0.01 high entropy alloy by powder-pack boronizing at 900 °C, 950 °C and 1000 °C for 4 h. The nanohardness (H), modulus of elasticity (E) and fracture toughness (KC) of the multiphase boride layers were determined based on the load–displacement (P-h) curves obtained in the nanoindentation tests. Three distinct regions were identified on the cross-sections of the produced layers: an outer layer consisting of MeB-type borides, an inner layer consisting of Me2B-type borides and the transition zone. The microstructural aspects of the layers were investigated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Detailed analysis of the influence of the chemical composition on hardness, elastic modulus and fracture toughness in the three regions indicated that the most critical factor influencing the mechanical properties was the presence of chromium, iron and cobalt borides in the microstructure. Especially the formation of chromium borides reduced the fracture toughness of the transition zone.

Improving the wear and corrosion resistance of martensitic stainless steel by paste boriding treatment

Surface hardening techniques of steel are of great practical interest for applications in the petroleum industry. The boriding technique is one of the most economical choices. In this work, a paste boriding process is performed to increase the wear and corrosion resistance of AISI 410 martensitic stainless steel. The surface wear and corrosion resistance of the steel were significantly improved via the paste boriding treatment. The microstructure of the borided layer consists of FeB and Fe2B, which are located in the external and internal layers of the borided layer, respectively. As the boriding temperature rises, the thickness of the borided layer increases, which at the same time leads to an increase in the number of voids.

Increasing corrosion resistance of AISI 1010 steel by boride coatings

AbstractBoriding is the process of coating the metal surface with a ceramic metal boride layer by the diffusion method. Iron borides, one of the metal borides, are called ceramics because they are covalently bonded compounds. Iron boride coatings contain strong Fe–B and B–B covalent bonds. In this study, the effect of boronizing on the corrosion resistance of AISI 1010 steel was investigated. Baybora‐1 which has recently been patented was used as boronizing agent. AISI 1010 steel was borided at 950°C for 2, 4, and 6 h using the solid method. The microstructure, hardness, and corrosion rate of the samples were investigated. The change in the corrosion rate of the samples was determined by the corrosion test specified in the ASTM G31‐72 standard. The results showed that the hardness of the iron boride layer formed on the surface as a result of the boronizing process was greater than that of the matrix. As a result of the boriding process, the hardness of the iron boride layer on the steel surface reached approximately eight times the hardness of the substrate matrix. The thickness of the iron boride layer on the steel sample surface was measured at 950°C for 2 and 6 h, respectively, as 45 ± 12 and 155 ± 13 µm. It was concluded that the boriding process increased the corrosion resistance of steel.

Electroless Deposition of Nickel-Phosphorus Composite Layer with Incorporated Amorph Boron Particles and Subsequent Heat Treatment for the Formation of Nickelboride

In an effort to decrease the operating cost in the manufacturing industries, industrial knives and large tools in the forming technology should possess characteristics that increase its lifetime. One such properties would be the high surface hardness and a possibility to improve this characteristic would be through boriding. Through this method, whereby boron powder or paste is spread on the tool surface before the workpiece is heated in the oven at 750 – 950 °C for 4 – 6 h, a diffusion process occurs between the boron paste and the substrate. Borides are formed in the workpiece until a depth of approx. 250 µm from the workpiece surface depending on the substrate type and the heat treatment parameters. Genel et al. attained a hardness value of around 1700 HV at 75 µm depth when they borided AISI W1 steel workpiece at 950 °C for 6h[1],[2],[3]. By boriding a nickel superalloy, Inconel 718, at 950°C for 6h, Campos-Silva et al. achieved approx. 2200 HV at 30 µm depth[4]. However this method is disadvantageous in terms of the high energy cost and the long treatment period.As an alternative, hard chrome layer that has a hardness value between 600 to 1200 HV[5],[6] can be electroplated on the workpiece. Besides having an improved wear protection, this chrome layer offers a good corrosion protection and can be produced with a lower cost since it does not need a thermal post-treatment to increase its hardness and hence this method is less energy intensive as boriding. Admittedly the application of chrome-VI ions in the hard chrome electrolyte is without special permission prohibited in the European Union since 2017 according to REACH[7] considering its carcinogenic properties[8],[9],[10]. Another possible method would be through composite coating. Many works have been done on electroless composite nickel coating with boron nitride, silicium carbide, diamonds, aluminium oxide and titanium oxide among others used as dispersoid. After a heat treatment at 400 °C for 1 h, the hardness of most of these coating increases significantly from around 700 HV to approx. 1100 HV[11].In the present study, the positive aspects of boriding and electroless deposition of nickel-phosphorus layer should be combined, so that a hard surface with a good wear resistant can be produced for industrial tools in a more efficient way. It is expected that lower heat treatment temperature and/or less treatment time is needed to achieve the same effect as boriding since boron particles are already homogenously distributed and have a shorter diffusion path in the thick composite layer. In addition to that, the hardness gradient throughout the heat-treated composite nickel coating should be much lower compared to boriding, especially when a high amount of boron particles is evenly distributed in the layer. The coating thickness, which will then be equated as boride layer thickness after sufficient heat treatment, can be manipulated with coating parameters and electrolyte type. Hence, through this combined method, a thicker boride layer is achievable by depositing a thicker composite nickel layer.Amorph boron powder of different sizes are used as dispersoid in the composite electroless nickel layer. The dependency of incorporated boron content in the composite layer with the particle content in the electrolyte, the particle size and the effect of ultrasound-assisted deposition is investigated. A homogenous particle distribution in the deposited layer and controllable incorporation of the boron particle in the nickel-phosphorus matrix are desirable. Furthermore, the agglomeration behaviour of the boron particle in the electrolyte is examined through laser doppler electrophoresis. The influence of the incorporated boron particle on the coating hardness and its wear resistance before and after heat treatment is studied by measuring it according to Vickers and with Calotester kaloMAX NT II. The effect of the heat treatment parameters with respect to the heat-treating temperature and time to the surface hardness and its wear resistance is investigated. At the conference results of the metallographic examinations, SEM-EDS and XRD analysis will be presented. Figure 1

Effect of Cr Addition on Properties and Tribological Behavior at Elevated Temperature of Boride Layers Grown on Borosintered Powder Metallurgy Alloys

Effect of Cr Addition on Properties and Tribological Behavior at Elevated Temperature of Boride Layers Grown on Borosintered Powder Metallurgy Alloys

The effect of process parameters and characterization for the laser cladding of cBN based composite clad over the Ti6Al4V alloy

In the present study, a metal matrix composite of nitride, boride, and oxide layer over the Ti6Al4V substrate has been formed by using high-quality reinforcement like cBN, TiO2, and Ti6Al4V. Response surface methodology (RSM) has been successfully implemented to investigate the effect of process parameters (laser power, scanning speed, and shielding gas flow rate) on the responses like clad layer thickness and micro-hardness value of the cladded part. Statistical analysis shows that laser power and scanning speed significantly influence layer thickness and microhardness. Further considering the optimal combination of process parameters, cladded surfaces with different percentage compositions of reinforcement are characterized. The clad shows different microstructures like needles, cylindrical rods, and short-length dendritic. These confirm the formation of a metal matrix composites of nitrides and borides (TiN, TiAlN, AlN, and TiB2) as the main constructive phase of the clad. Further analyzing the binding energy of these phases through XPS, the formation of the compounds exhibits higher intensity. These enhance the hardness as well as wear resistance properties of the clad. The coefficient of friction in the cladded surfaces is less than the base material due to anti-wear chemical compounds like boride and nitride. However, spalling craters and wear debris are found in cladded samples.

Research on Properties and Growth Kinetics of Boride Layer of Fe-Based Powder Metallurgy Material Boriding Strengthened with Rare Earth

The Fe-based powder metallurgy material was directly sintered and boriding with CeO2 respectively by a pack powder boriding method to obtain a specimen with a boride layer. Boriding treatment was performed at 1123–1323 K for 3–10 h. The morphology and the thickness of the boride layer were observed with a ultra-depth-of-field microscope and a scanning electron microscope (SEM). The phase composition of the boride layer was analyzed by X-ray diffractometer. The quality of the bonding strength between the boride layer and the substrate was evaluated by the Rockwell-C adhesion test. The results showed that boriding with 2 wt% CeO2 will inhibit the boriding treatment at low temperature and promote it at high temperature. Boriding with 4 wt% CeO2 will inhibits the boriding process at both low and high temperature, and the inhibition becomes stronger as the temperature increases, the inhibiting effect at 1323 K is 9 times that at 1123 K. The quality of the bonding strength of the boride layer with CeO2 is better than that specimen without CeO2 and the quality of the bonding strength with 2 wt% CeO2 is approved by the HF3 grade according to the specifications.

Diffusion kinetics and boronizing of high entropy alloy produced by TIG melting reverse suction method

ABSTRACT In this study, CrMnFeCoNi high entropy alloy was produced using TIG melting reverse vacuum method using a shielding gas atmosphere. Produced samples were boronized with pack boriding method at 1173, 1223, 1273 K temperatures and for 2, 4 and 6 h. As a result of the experiments, the morphology of the boride layers formed on the high entropy alloy surfaces was investigated by SEM microscope. The hardness values were measured with a microhardness device and the phases formed on the boride layer were determined by the XRD method. In addition, the thickness and growth kinetics of the boride layer on the high entropy alloy were investigated. The boride coating thickness ranges from 38 µm to 268 µm. FCC crystal structure is present in the HEAs produced in XRD examinations and the hardness value was determined as 242 HV0,05 (± 15). B-dependent phases of Cr, Mn, Fe, Co, Ni were obtained in the coating layer and the hardness value was measured as 2250 HV0,05 maximum. The boride layer activation energy value of the coated HEA was calculated as 376,465 kJ/mol.

Effect of chemical-heat treatment on the properties of titanium

The aim of this study is to evaluate the properties and microstructure of pure titanium after its chemical heat treatment (CHT) by boriding and nitriding. Nitriding and boriding were both done in powder backfill for ten hours. The temperature of the nitriding was 550 °C. The temperature of the boriding was 1000 °C. Both processes led to the creation of a thin surface layer of nitrides and borides which affected wear resistance and also they affected corrosion resistance of the surface of the analyzed samples.

Evaluation of Boride Layers on C70W2 Steel Using a New Approach to Characterization of Boride Layers.

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 the boronizing parameters. This study has shown that characterization based on the volume fraction of the boride phase offers advantages over the conventional method based on the average thickness of the layer.