Boride layers were grown on the surface of a Co1.19Cr1.86Fe1.30Mn1.39Ni1.05Al0.17B0.04 high-entropy alloy (HEA) by boronizing at temperatures of 900, 950 and 1000 °C for 4 h using nanosized ...boronizing powders. Characterizations were carried out by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), microhardness measurements, nanoindentation tests, surface profilometry and ball-on-disc type wear tests. The tribocorrosion behavior of the boronized HEAs and the untreated alloy were investigated in air and in 5% HCl. Microstructural examinations revealed complex metal boride layers on the surfaces of the boronized HEAs, consisting mainly of Cr2Ni3B6, Fe0.4Mn0.6B, Cr0.4Mn0.6B and CrFeB2 phases. The boride layers were silicide-free, with thickness and hardness values of 31.95–64.36 μm and 23.49–28.09 GPa, respectively. The boronized HEAs exhibited reduced friction coefficients and low wear losses in both ambient air and 5% HCl compared to the untreated HEA. Due in part to the lubricating and cooling effect of the solution, the untreated HEA and the boronized HEAs showed reduced wear losses in 5% HCl compared to air. In air, the wear mechanism of the boronized HEAs was abrasive wear combined with polishing, while in the as-cast HEA the wear mechanism was abrasive wear accompanied by plastic deformation. In 5% HCl, the wear mechanism of the boronized HEAs was abrasive wear accompanied by oxidation and pitting, while in the as-cast HEA the wear mechanism was abrasive wear combined with pitting.
•A Co1.19Cr1.86Fe1.30Mn1.39Ni1.05Al0.17B0.04 HEA was successfully boronized using nano-sized boronizing powders.•The compact boride layers grown on the surfaces of the HEAs exhibited high hardness values.•The wear performance of the HEA was improved with the boronizing treatments.•The wear environment had a significant effect on wear behavior.•Nano-sized boronizing powders open new possibilities for the boronizing of HEAs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Silicide-free boride layers were grown on Inconel 718 Ni-based superalloy surface at 850 °C, 950 °C, and 1050 °C for 2, 4, 6 hour by the powder pack-boronizing process using nano-sized B
4
C powders. ...The coatings were examined using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, 3D profilometry, and microhardness measurements. Wear experiments were carried out on untreated and boronized Inconel 718 using a ball-on-disk tribometer under dry sliding conditions at temperatures of 25 °C, 400 °C, and 750 °C. An increase in boronizing temperature and duration increased the thickness and hardness of the obtained boride layers, which resulted in low coefficient of friction values and decreased wear rates. Scanning electron microscopy images of the worn surfaces revealed two-body abrasion as the effective wear mechanism in the untreated samples, and three-body abrasion assisted by microcracking and spalling as the dominant wear mechanism in the boronized samples. A transition from mild to severe wear occurred in the untreated samples, while wear rates remained low in the boronized samples up to 750 °C. In conclusion, boronized Inconel 718 was capable of sustaining its boride layers under 5 N for 1800 m at wear-test temperatures up to 750 °C.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Arc-directed energy deposition (Arc-DED), also commonly referred to as wire arc additive manufacturing (WAAM), is a cost-effective 3D metal additive manufacturing process in which large metallic ...parts can be produced due to high deposition rates. Stainless steels, widely used in many areas due to their excellent corrosion resistance, are one of the most produced materials by the WAAM method. However, stainless steels have low surface hardness. Moreover, the high heat input in the deposition process in WAAM sometimes causes the mechanical properties of stainless steels to be lower than casting or wrought stainless steels. These considerations limit the use of WAAM stainless steels, especially in abrasive environments. For this purpose, 307ER stainless steel produced by WAAM method was subjected to homogenization and boriding process simultaneously at 1000 °C for 1 h and the effect of applied heat treatment on microstructure, phase components, hardness and wear resistance was investigated. The results showed that with the boriding process, a 30 μm thick boride layer consisting of FeB, Fe2B, Cr5B3 and MnB phases with a hardness of 21.5 GPa and a modulus of elasticity of 310 GPa was formed in addition to the dissolution of interdendritic regions in the as-built structure and a complete homogenization of the microstructure. Furthermore, owing to the high hardness and elasticity modulus in addition to the boride layer's self-lubrication properties obtained on the WAAM samples surfaces, 31.84 times and 8.06 times increased in wear resistance at room temperature and 500 °C temperature, respectively, and a decrease in friction coefficients was obtained. Moreover, the results showed that the simultaneous homogenization and boriding processes of stainless steels produced by the WAAM method would improve their microstructure and tribological behavior. This way, these steels can be used in wider areas of application.
•GMAW-based WAAM ER307 stainless steel components were successfully manufactured.•Boride layers improved the surface hardness of WAAM ER307 up to 7 times.•The self-lubrication properties of borides provided lower COF at 25 °C and 500 °C.•Increase in surface hardness resulted in an increase in wear resistance up to 500 °C.•Boriding has the potential to open up new possibilities for additive-manufactured metals.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, Ni-based Inconel 718 coatings were additively manufactured on the surface of AISI H13 work tool steel by electro-spark deposition (ESD). Some of the electro-spark deposited samples ...were boronized at 1000 °C for 5 h to evaluate the effects of boronizing on microstructure, high-temperature wear, and corrosion resistance. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), 2D profilometry, wear and electrochemical corrosion testing was used to characterize the surfaces, microstructures, microhardness, some mechanical properties, high-temperature wear, and corrosion resistance of the applied coatings. Wear tests were performed at room temperature and 650 °C, and corrosion tests were performed in 3.5% NaCl at room temperature, considering the applications of AISI H13 and Inconel 718 alloys. The characterization studies showed evidence of microcracking and oxidation in the as-deposited Inconel 178 coatings. In the boronized Inconel 718 coatings, the oxides and microcracks were slightly reduced. The hardness of the boronized Inconel 718 coating was increased to about four times the hardness of the as-deposited Inconel 718 coating, and this significantly improved its wear resistance. The highest wear resistance was achieved with the boronized coating, while the best corrosion resistance was obtained with the as-deposited coating. The improvements in wear resistance provided by boronizing have the potential for expanding the applications of Inconel 718 coatings in machine components.
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•AISI H13 tool-work steel exposed to combined electro-spark deposition and boronizing processes.•The microstructure, friction, wear and corrosion behaviors of different surfaces were compared and analyzed.•The irregularly shaped oxides and cracks in the ESD coatings were healed and the microstructure was refined by boronizing.•Electrospark deposition and boronizing improved corrosion and high-temperature wear resistance of AISI H13 steel.•Boronizing offers an alternative to laser surface modifications in improving the mechanical properties of ESD coatings.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Distaloy SA is a sponge iron powder (nominal composition: Fe-1.75Ni-1.5Cu-0.5Mo) widely used in the production of powder metallurgy (P/M) parts in the automotive industry. In this study, Distaloy SA ...powders were sintered in two different atmospheres, one consisting of pure Ar gas (traditional sintering) and the other consisting of a mixture of 90 wt.% B
4
C and 10 wt.% NaBF
4
powders (borosintering). To investigate the effects of the different sintering atmospheres, the P/M samples were characterized using density measurements, surface roughness tests, scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, microhardness measurements, nanoindentation experiments, wear tests and corrosion tests. On the surface of the borosintered samples, a 160-325 µm thick double-phase FeB + Fe
2
B boride layer was formed. The hardness (1405-1688 HV) and elastic modulus (122.21-162.42 GPa) of the surface were significantly improved with the borosintering treatment compared to conventional sintering (215-250 HV, 63.28-94.86 GPa). Borosintering also provided low friction coefficient values and an increased wear resistance compared to conventional sintering. A significant increase in corrosion resistance was also observed with the borosintering treatment in three different solutions. The corrosion rates of both sintered and borosintered samples were ranked as NaCl < HCl < H
2
SO
4
. The borosintered samples displayed superior corrosion resistance compared to the sintered samples, especially in the acid solutions. The results of this study show that significant cost savings can be achieved by combining the boriding and sintering treatments in a single borosintering process.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
CoCrFeNiAl0.25Ti0.5 high entropy alloy alloys (HEA), produced by powder metallurgy were subjected to boriding to improve their mechanical properties. Sintering was carried out at 1200 °C for 2 h in ...Ar, and boriding was performed at 900, 1000 and 1100 °C for 2 h using a 90 wt% B4C + 10 wt% NaBF4 boriding powder mixture. Microstructures, densities, surface roughnesses, and mechanical properties (hardness, fracture toughness and nanoindentation responses) of the samples were investigated. FCC, BCC and sigma phases had been observed after sintering, whereas complex metal borides were formed on the surfaces after boriding. Relative density values were between 85% and 90%. Significant increases in surface hardness were observed after boriding due to formation of hard, silicide-free boride layers. The boride layer thickness and hardness increased with increasing boriding temperature. The elastic modulus of the surface of the sintered sample (47.07 GPa) increased with the boriding process to values in the range of 140–151 GPa. Fracture toughness values between 3.57 and 4.25 MPa m1/2 were obtained in borided samples, and increasing the boriding temperature reduced the fracture toughness.
•P/M produced CoCrFeNiAl0.25Ti0.5 high entropy alloy was successfully borided.•Density, roughness, hardness, fracture toughness, etc. Properties were examined.•255–363 μm thickness coating layer was obtained in the borided samples.•The 531 H V microhardness value increased to 1461–1646 by boriding.•The fracture toughness values of the boride layer were between 3.57 and 4.25 MPa m1/2.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The role of bovine calf serum (BCS) related to the functional performance of synovial fluid on the tribological behavior of borides grown on cobalt–28chromium–6molybdenum (Co–28Cr–6Mo) alloy used in ...orthopedic prostheses is not known yet. Here, the borides were grown on Co–28Cr–6Mo surface for 5 and 7 hours at 975 °C using 90 wt pct boron carbide (B
4
C) and 10 wt pct sodium tetrafluoroborate (NaBF
4
) powders. The borides were characterized by X-ray diffractometer (XRD), nanoindentation, scanning electron microscope (SEM) and energy dispersive spectroscope (EDS). The tribological performance of the borides was evaluated using a ball-on-disk type tribometer in dry-sliding condition and different biological fluids (phosphate buffered saline (PBS) and BCS). The thickness, nanohardness and elastic modulus values of the borides composed of a bilayer Co
2
B and CoB phases were observed to be 33.3 to 40
µ
m, 22.34 to 24.30 GPa and 224.46 to 229.27 GPa, respectively. Following the boriding process, the volume loss of Co–28Cr–6Mo decreased from 0.275 to 0.122-0.142 mm
3
owing to the high hardness and elastic modulus of the formed boride layers. The lubricating effect of PBS and BCS fluids has a great influence on the friction and wear performance of the boride layers. With the introduction of PBS lubricant into the tribosystem, the worn volume and COF of the borides significantly decreased from 0.122-0.142 to 0.014 mm
3
and from 0.68-0.75 to 0.21-0.25, respectively. Plasma proteins present in BCS lubricant managed to reduce these values even further and showed a COF of 0.09 and the worn volume of 0.002 to 0.003 mm
3
. SEM and EDS analyses showed that the main failure mechanism of the borides was changed from oxidation-assisted delamination in dry-sliding condition to micro-scratches in BCS lubricant. The superior wear and friction performance of the borides (grown on Co–28Cr–6Mo) in BCS lubricant suggests its potential usage for orthopedic implant products although further
in-vitro
and
in-vivo
studies are needed to verify this potential.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This study explores the transformative potential of boriding to enhance the tribocorrosion resistance of mooring chain steel for offshore environments. The boride layers formed at various ...temperatures (800 °C, 900 °C, and 1000 °C) for 1 h, revealing high hardness (17–21 GPa). X-ray diffraction confirmed dual-phase FeB and Fe2B borides, contributing to superior mechanical properties. Energy-dispersive X-ray spectroscopy showed clear phase boundaries. Potentiodynamic data demonstrated improved corrosion and tribocorrosion resistance, particularly at higher boriding temperatures. Mechanical effects played a pivotal role in tribocorrosion behaviour, emphasizing the need to optimize boriding process temperatures. Electrochemical impedance spectroscopy highlights the 900 °C-1 h sample as offering excellent corrosion resistance. This study underscores boriding's potential to enhance the tribocorrosion resistance of offshore mooring chain steel.
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•Cl ions, cracks, and stress worsen the coating's tribocorrosion susceptibility.•The mechanical effects were decisive in wear-corrosion synergism.•The passive layer reduced the friction coefficient.•Borided steel showed significantly lower corrosion rates.•Optimizing boriding temperature can further enhance tribocorrosion resistance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The microstructural and mechanical properties of FeAl-NbC were investigated.•Low hardness and brittleness of Fe-Al intermetallics mitigated by growth NbC.•Graphite nodules were transformed into NbC ...with the formation of NbC-FeAl.•NbC formation in FeAl increased the hardness and dislocation densities.•The formation of NbC in Fe-Al coatings has a significant effect on wear resistance.
Iron-aluminide (Fe-Al) intermetallics are characterized by their high-temperature oxidation resistance. However, their use in tribo-corrosive environments is limited due to their low hardness and brittle nature. To overcome this weakness, the feasibility of forming composite coatings (NbC-FeAl) by intercalation of refractory NbC particles into Fe-Al coatings by thermo-reactive diffusion technique and its effect on high-temperature wear behavior was investigated in this study. The coatings obtained underwent comprehensive characterization using scanning electron microscopy, X-ray diffraction, microhardness measurements, and ball-on-disc wear tests, providing valuable insights into their properties. The characterization studies showed that increasing the growth of NbC in the intermetallic iron-aluminide content resulted in a slight increase in the hardness and a decrease in the thickness of the iron-aluminide layer. Moreover, the formation of NbC in Fe-Al coatings increased the dislocation densities of the coatings, resulting in an improvement of wear resistance 2.7 times at room temperature and up to 3.5 times at 500 °C. While different wear mechanisms occurred in coated samples at room temperature, the dominant wear mechanism at 500 °C evolved into an oxidatively supported adhesive wear mechanism. This study showed that Fe-Al coatings exhibited better wear response at both room and elevated temperatures when reinforced with NbC.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A high entropy alloy with face-centered cubic structures was successfully boronized by nano-sized boronizing powders.•The microstructural and mechanical properties of the grown borides ...investigated.•The hardness and elasticity modules of FCC high entropy alloys with low surface hardness were developed by boronizing.•The friction and wear performance of the HEA was improved with the boronizing.•The wear environment had a significant effect on wear behavior.
High-entropy alloys (HEAs) with face-centered cubic (FCC) structures exhibit high toughness and corrosion resistance, but their average strengths and relatively low wear resistance can limit their engineering applications. In this study, FCC Al0.07Co1.26Cr1.80Fe1.42Mn1.35Ni1.10 HEAs were boronized for 4 h at temperatures of 900, 950, and 1000 °C to form hard, protective metal borides on their surfaces. The microstructural characteristics of the borides formed were examined using X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The mechanical properties of the boride layers were studied by nanoindentation measurements, and the tribological performances of the layers were evaluated by ball-on-disk type wear tests in air, 3.5% NaCl and 5% H2SO4. Irrespective of the boronizing temperature, (Fe0.4Mn0.6)B, (Cr0.4Mn0.6)B, (CoFe)B2 and Cr2Ni3B6 phases were detected in the surfaces of the boronized samples. The surface hardnesses of the boronized samples reached nearly ten times the hardness of the as-cast HEA. The borides were effective in reducing friction as well as wear. Increasing the boronizing temperature increased the thicknesses of the coatings and further improved wear characteristics. Wear rates in 5% H2SO4 were generally higher than the wear rates in 3.5% NaCl, but the highest wear rates were observed in air.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
