Rockwell-C Adhesion Test Research Articles

Microstructural transformation and failure mechanism of CrN/CrTiSiN coatings experienced annealing post-treatment

There are great efforts for enhancing the characteristics of PVD multilayered coatings and one solution could be heat treating the coated part. The current research analyzed the effect of annealing temperatures on the microstructural transformation and failure mechanism of CrN/CrTiSiN multilayered coatings. The coatings were annealed in air at temperatures ranging from 500 °C to 1000 °C for 1 h. The characterization methods included XRD, XPS, FESEM, EDS, and Rockwell-C adhesion tests. The findings indicated that the as-deposited coating exhibited a consistent structure of the CrN phase. During the process of annealing from 500 to 700 °C, the CrN phase transforms into the Cr2N phase. At 800 °C, the structure is fully composed of Cr2N. At 900 °C, the elevated annealing temperature causes the Cr2N phase to change into the Cr2O3 phase. The volume fraction of the Cr2O3 phase increases until the temperature reaches 1000 °C. The results showed that the transition of Cr2N → Cr2O3 within the coating's thickness would lead to peeling off the coating due to an increase in the lattice volume. The EDS mapping shows that raising the annealing temperature for a constant time will result in more oxygen infiltration into the coating's thickness.

TiSZ-reinforced hydroxyapatite coatings on magnesium substrate with titanium interlayer

ABSTRACT In this study, pure and 10% wt. Titania-Stabilised Zirconia (TiSZ) -reinforced Hydroxyapatite (HA) coatings were deposited on magnesium substrate using plasma spray as a single layer and double layer with an HVOF sprayed Ti bond coat. The coated specimens were characterised by X-ray diffraction (XRD) analysis, and scanning electron microscopy equipped with energy dispersive spectroscopy (SEM, EDS). Rockwell-C adhesion and scratch tests were performed. The corrosion behaviours in simulated body fluid (SBF) of coatings were investigated by an electrochemical corrosion test. Analyses confirmed successful coating with a dense titanium buffer layer. The double-layered HA-titanium combination offered superior corrosion resistance compared to single layers. While adding TiSZ enhanced adhesion, it compromised scratch resistance. The titanium bond coat had minimal impact on adhesion and cohesion behaviour of coatings.

Effects of nitrogen flow ratio on the mechanical and anticorrosive properties of cosputtered (TiZrHfTa)Nx films

In this study, TiZrHfTa films were cosputtered through cyclical gradient composition deposition by using four single-element targets connected to direct-current power supplies. Multilayered and columnar structures formed at low and high rotation speeds of the substrate holder (RH), respectively. (TiZrHfTa)Nx thin films were then prepared through reactive cosputtering by using Ar/N2 mixed gas. A high RH value resulted in these films having homogeneous structures. Without the addition of reactive nitrogen gas, the fabricated metallic Ti0.24Zr0.23Hf0.27Ta0.26 film exhibited a valence electron concentration of 4.26, which resulted in the formation of a body-centered cubic (bcc) phase; a hardness of 4.7 GPa; and an elastic modulus of 104 GPa. (TiZrHfTa)Nx films with stoichiometric ratios (x) ranging from 0.59 to 0.97 were obtained by adjusting the reactive gas ratio fN2 (N2/(N2 + Ar)) from 0.1 to 0.7. The introduction of N into the TiZrHfTa crystallites caused the bcc phase to transform into a face-centered cubic phase and enhanced the mechanical properties of the films, with their hardness and elastic modulus increasing to 13.8–25.5 and 235–290 GPa, respectively. Nanoindentation, scratch, Rockwell-C adhesion, and potentiodynamic polarization tests indicated that among the prepared (TiZrHfTa)Nx films, the (Ti0.17Zr0.25Hf0.20Ta0.38)N0.75 film exhibited the best mechanical and anticorrosive properties. Target poisoning accompanied by defect formation affected the mechanical properties of the (TiZrHfTa)Nx films. The anticorrosive properties of the (TiZrHfTa)Nx films were dominated by the high-entropy effect through alloying with Ta and the adhesion strength between the films and substrates.

Enhancing mechanical and tribological performance of CrN/CrTiSiN coating through annealing treatment

The primary objective of the present investigation is to examine the effects of air annealing on the mechanical, tribological, and structural properties of multilayer CrN/CrTiSiN coatings. The deposition of CrN/CrTiSiN multilayer coatings on a Ti6Al4V substrate was carried out using CAE-PVD technique. Subsequently, the as-deposited coatings were subjected to annealing in ambient air environment at a temperature of 600 °C for 1 h. The characterizaion purposes were achieved by XPS, XRD, FESEM, nanoindentation, Rockwell-C adhesion tests, and pin-on-disk wear tests. The results suggest that the annealing process led to the development of new Cr2N, Cr2O3, and SiO2 phases. The coating hardness increased from 21.5 GPa to 25.3 GPa by annealing process. The findings from the pin-on-disc experiment indicate that the wear resistance of the annealed coating exhibited superior performance when compared to both the as-deposited coating and the substrate. The improvment could be attributed to the annihilation of the residual stress and the formation of new phases on the surface.

Tape Casting and Characterization of h-BN/PU Composite Coatings for Corrosion Resistance Applications

In the present work, a slurry of polyurethane (PU) was prepared by adding various contents (3 and 8 wt.%) of hexagonal boron nitride (h-BN). Ethanol was utilized as a solvent to reduce the viscosity and sticking effect of the PU. The mixture was then applied as polymer matrix composite (PMC) coating on steel substrates via tape casting. The prepared coatings were characterized for their structure, adhesion and thermal properties, and corrosion resistance characteristics. The structural and morphological features of the h-BN/PU composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Rockwell-C adhesion tests were conducted to examine the adhesion between the substrate and composite coating. The potentiodynamic polarization tests were utilized to assess the anti-corrosion performance of composite coatings when applied and steel substrates. The results exhibited that the inclusion of h-BN filler (3 wt.%) could effectively enhance the anti-corrosion performance of the h-BN/PU composite. The reason for the improvement in corrosion properties was attributed to lower surface roughness, uniform distribution and great adhesion strength of PU/3 wt.% h-BN composite. Furthermore, the PU/3 wt.% h-BN composites showed relatively improved thermal stability and higher glass transition temperature (Tg). However, further loading of h-BN contents (8 wt.%) deteriorates the thermal and corrosion resistance properties of the composite due to the clustering of h-BN, which creates localized areas of increased corrosive activity.

Assessment of applied voltage on the structure, pore size, hardness, elastic modulus, and adhesion of anodic coatings in Ca-, P-, and Mg-rich produced by MAO in Ti–25Ta–Zr alloys

This work aims to modify the surface of the Ti–25Ta-xZr (x = 0, 25, and 50 wt%) system alloys through micro-arc oxidation (MAO) to incorporate calcium, phosphorus, and magnesium ions in the oxidized layer deposited. The MAO surface modification was performed by changing the limited voltage applied to system (200, 250, and 300V). Structural characterizations by X-ray diffraction and X-ray photoelectron spectroscopy showed that the formed MAO coatings comprise TiO2, Ta2O5, ZrO2, and CaCO3 oxides. Voltage inhibits the formation of Ta2O5 and CaCO3 phases and decreases the incorporation capacity of Ca, P and Mg ions. The MAO coatings' topography, thickness, and roughness, analyzed by scanning electron microscopy and confocal microscopy techniques, showed that increasing the voltage tends to increase pore sizes and reduces film thickness; conversely, it decreases the number of pores per μm2. Regarding hardness and elastic modulus, adding Zr increases the MAO coating's hardness due to the formation of ZrO₂. However, increasing the voltage decreases the MAO coatings' hardness due to the formation of the compound CaCO3. The MAO process increased the elastic modulus of the Ti–25Ta-xZr bulk alloys. Finally, the adhesion of the films was analyzed by the Rockwell-C adhesion test. The results showed a good adhesion of MAO coatings to Ti–25Ta-xZr substrates.

Investigation of the effect of boriding on the wear behaviour of AISI 1050 carbon steel

In this study, AISI 1050 carbon steel samples were boronized with the powder pack boriding technique at 875°C for 2, 4 and 6 hours using Ekabor 2 boriding powder. The boride layer thicknesses obtained with the boriding time increased and after 2, 4 and 6 hours of boriding, a 30.6, 40.0 and 71.8 µm boride layer, predominantly composed of Fe2B phase, was obtained. Boride layers were formed in tooth-like morphology. Thanks to this boride layer, the surface hardness of the substrate was improved 6.2-6.4 times and a maximum surface hardness of 1543.8 HV was reached. With the Daimler-Benz Rockwell-C adhesion tests, it was determined that the adhesion quality of the boride layer was generally at the HF1 level. With the boriding carried out, the specific wear loss of AISI 1050 steel was reduced from 421.25 mm3/Nm x10-6 to 17.67 mm3/Nm x10-6, and the wear resistance was increased approximately 24 times.

(Cr1-xAlx)N Coating Deposition by Short-Pulse High-Power Dual Magnetron Sputtering.

The paper deals with the (Cr1-xAlx)N coating containing 17 to 54 % Al which is deposited on AISI 430 stainless steel stationary substrates by short-pulse high-power dual magnetron sputtering of Al and Cr targets. The Al/Cr ratio in the coating depends on the substrate position relative to magnetrons. It is shown that the higher Al content in the (Cr1-xAlx)N coating improves its hardness from 17 to 28 GPa. Regardless of the Al content, the (Cr1-xAlx)N coating manifests a low wear rate, namely (4.1-7.8) × 10-9 and (3.9-5.3) × 10-7 mm3N-1m-1 in using metallic (100Cr6) and ceramic (Al2O3) counter bodies, respectively. In addition, this coating possesses the friction coefficient 0.4-0.7 and adhesive strength quality HF1 and HF2 indicating good interfacial adhesion according to the Daimler-Benz Rockwell-C adhesion test.

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.

Tribological and adhesion properties of microwave-assisted borided AISI 316L steel

Abstract In this study, AISI 316L stainless steel alloy samples were borided with powder-pack boriding method using Ekabor II powder with the support of a microwave furnace with a power of 2.9 KW and a frequency of 2.45 GHz. Boriding was carried out at 850, 900 and 950 °C temperatures for 2, 4 and 6 h of operation. A distinct diffusion barrier consisting of Fe–Ni–Si elements was detected in borided samples at 950 °C for 4 and 6 h. As a result of the Daimler Benz Rockwell-C adhesion tests, regions with insufficient adhesion strength were detected in these samples. In other samples, adhesion qualities between boride layers and substrate were in the range of HF1–HF3. The lowest specific wear rates were determined as 5.208 (mm3 Nm−1) × 10−6 and 5.210 (mm3 Nm−1) × 10−6 for the samples borided for 6 h at 850 °C and 4 h at 900 °C, respectively. It was determined that the increase in thickness of the brittle FeB compound increased the wear with the three-body abrasive wear mechanism.

The effects of boriding process on tribological properties and corrosive behavior of a novel high manganese steel

• Borided HMS unexpectedly exhibited saw-tooth morphology. • Borided HMS has superior adhesion properties. • Boriding increases service life, wear and corrosion resistance of HMS. In this study, wear and corrosion behavior of a novel borided high manganese steel (HMS) produced by the researchers was investigated. After the sheets were cold-rolled, they were annealed. HMS was borided at 850, 900, and 950 °C for 2, 4, and 6 h through the pack-boriding process. Borided HMS uncommonly exhibited a saw-tooth morphology like low alloy steels due to similar crystal structures of MnB and FeB. XRD analysis showed the existence of SiC, FeB, MnB and Fe 2 B phases. The present study indicated a silicon-rich zone by EDX mapping. The formation mechanism of silicon-rich zones was explained and expressed with the term “compact transfer of silicones”. The boriding time and temperature increased the thickness of the boride layer from 26.13 μm to 109.04 μm. The highest hardness value was observed in sample 5 (1757 HV 0.05 ). The activation energy of borided HMS was quite low compared to several high alloy steels in the literature. Daimler-Benz Rockwell-C adhesion test showed that adhesions of borided HMS surfaces were sufficient. The "egg-shell effect" that emerge due to the high silicon rate did not occur. In the wear tests applied under 5, 10, and 15 N loads, the borided HMSs exhibited a better wear resistance compared to the base metal (BM). However, the wear test was applied under 5 N load and BM had a better performance than several borided HMSs because of the phase transformations. In general, the borided samples had lower corrosion rates compared to the unborided ones.

Wear Behavior of Borided Cold-Rolled High Manganese Steel

In this study, a novel high-manganese steel (HMS) was borided at 850, 900 and 950 °C for 2, 4, and 6 h by the pack boriding process. Contrary to previous literature, borided HMS uncommonly exhibited saw-tooth morphology like low alloy steels, and manganese enhanced the boron diffusion. Another striking analysis is that the “egg-shell effect” did not occur. The present study demonstrated the silicon-rich zone for the first time in the literature by EDX mapping. Moreover, the formation mechanism of silicon-rich zones was explained and termed as “compact transfer of silicones (CTS)”. XRD analysis showed the existence of FeB, Fe2B, MnB and SiC phases. The boriding time and temperature increased the thickness of the boride layer from 31.41 μm to 117.65 µm. The hardness of the borided layer ranged from 1120 to 1915 HV0.05. The activation energy of borided HMS was found to be a very low result compared to high alloy steel investigated in the literature. The Daimler-Benz Rockwell-C adhesion test showed that adhesions of borided HMS surfaces are sufficient. The dry sliding wear tests showed that boriding treatment increased the wear resistance of untreated HMS by 5 times. The present study revealed that the boriding process extended the service life of HMS components.

Adhesive Behavior of the Pack-Borided AISI 304L Steel with Microwave Hybrid Heating

Pack-boriding was applied to AISI 304L stainless steel material at temperatures of 850, 900 and 950 °C for 2, 4 and 6 hours with microwave hybrid heating method. The morphology of the boride layer formed on the surface of the samples was examined by optical microscope, and the phases formed in the layer were determined by XRD. The analysis of the adhesive strength of the boride layer to the substrate material was carried out by the Daimler-Benz Rockwell-C adhesion test. The tests were repeated at least 3 times for each of the pack-borided samples at all process temperatures and times. After the adhesion tests, macro and SEM images of indentation traces were taken. By analysing the indentation craters, it has been determined whether the damages are acceptable or not with reference to the VDI 3198 standard. The indentation craters formed on the pack-borided AISI 304L stainless steel sample surfaces at 850 °C with microwave hybrid heating method in all process times, for 2 and 4 hours at 900 °C, and 2 hours at 950 °C have the best adhesion quality in the HF1 category of the VDI 3198 norm.

Bactericidal silver-doped DLC coatings obtained by pulsed filtered cathodic arc co-deposition

Diamond-like carbon (DLC) coatings have been extensively studied over the last two decades in the field of materials engineering. The addition of effective bactericidal agents like silver suggests the potential application of silver-doped DLC coatings in the biomedical sector. In this paper, DLC coatings containing about 2 at. % Ag were grown on CoCrMo substrates by pulsed filtered cathodic arc co-deposition using pure graphite and silver targets. Morphology, structure and chemical composition of the coatings were characterized by SEM, XPS, XRD, Raman and HRTEM. Wettability and surface free energy were also measured. Mechanical properties were analyzed by means of nanoindentation and Rockwell-C adhesion tests. Corrosion resistance of coated and uncoated samples was determined by potentio-dynamic polarization tests in Hank's solution. Cytotoxicity and antibacterial activity against S. aureus and P. aeruginosa were also studied. For comparative purposes, nitrogen-doped DLC coatings obtained by RF magnetron sputtering were also prepared and characterized. Well-adhered and corrosion resistant Ag-DLC nanostructured coatings of up to 1.5 μm thick and 21 GPa in hardness were obtained. The doping concentration of silver studied in this work seems to be optimal for the preparation of non-cytotoxic coatings with a significant bactericidal activity.

Synthesis of molybdenum oxide on AISI-316 steel using cathodic cage plasma deposition at cathodic and floating potential

This study aims to synthesize a molybdenum oxide coating through cathodic cage plasma deposition (CCPD), employing a molybdenum cathodic cage and evaluating both cathodic and floating potentials treatment. Structural, morphological, and wear properties of coated AISI 316 samples are investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, Rockwell-C adhesion test, and ball-on-disc wear tester. Cathodic potential treatment results in a coating containing agglomerated nanostructures (spherical nanoparticles) composed by molybdenum oxide (MoO3), iron-oxide (Fe2O3), Fe2Mo3 and Fe3Mo phases. The coating generated by floating potential mainly contains molybdenum oxide (MoO3) phase and shows homogeneously dispersed microplatelets with quite a regular shape. The Rockwell-C adhesion test showed that the layers on both samples exhibit good adhesion strength with the substrate. The samples treated at floating potential reveal better wear resistance and lowest/smooth friction coefficient. This shows that molybdenum oxide coating by CCPD using floating potential can be used as a solid lubricant in tribological applications.

Examination of Wear and Rockwell-C adhesion Properties of Nitronic 50 Steel Coated with Pack Boriding Method

The Nitronic 50 steel is a nitrogen containing stainless steel, which has a high corrosion resistance, and high strength but its surface resistance against wear is low, making it extremely limited to use in areas subject to wear. In this study, in order to improve the material surface and to investigate its effect on tribological properties, boronizing process was carried out by used pack boriding method at 850 ° C, 900 ° C and 950 ° C for 4 hours. As a result of coating process, the boride layer has a smooth and flat structure in SEM investigations, the coating thickness varies between 9 µm and 36 µm and the boride layer thickness increases with increasing temperature. While the hardness of the uncoated material was around 250 HV0.05, the surface hardness of the material reached up to 1.712 HV0.05 with the coating process and increased about 7 times. According to XRD analysis, the surface of the coating layer consisted of phases FeB, CrB, Ni3B, Fe2B, Cr2B and MnB. Wear behavior was performed by ball-on-disk wear test in dry environment. The friction coefficient and wear rate decreases with increasing temperature, while the wear resistance is increased by 20 times compared to unboronized sample. When the wear tracks were examined, the uncoated Nitronic 50 had an adhesive wear mechanism, on the other hand the boronized samples had an adhesive and abrasive wear mechanism together. The Rockwell-C adhesion test was carried out under a load of 1.471 N and the resulting surface damages were evaluated according to the quality map. Boronized steel at 850 °C is defined as HF3 type, at 900 °C and 950 °C at boronized steel it is defined as HF4 type and adhesion is acceptable.

Mechanical properties and kinetics of boride layers on AISI D2 steel produced by plasma paste boriding

In the present study, the AISI D2 steel has been treated by the plasma paste boriding process using a gas mixture of 70% H2-30% Ar with 70% of borax and 30% SiC. The boriding treatment has been carried out at 700, 750 and 800 °C for an exposure time of 3 to 7 h. The plasma paste borided samples have been investigated by various techniques such as scanning electron microscopy, optical microscopy, XRD analysis, micro-hardness Vickers and the rockwell-C adhesion tests. The fracture toughness has also been measured on the plasma paste borided samples under different values of indentation load. From a kinetic point of view, the boride layers have obeyed the parabolic growth law. The value of boron activation energy for AISI D2 steel has been estimated as 130 kJ mol–1 using our experimental results. In addition, this obtained activation energy has been compared to the literature data.

Evaluation of Chromium Carbide Coatings on AISI 52100 Steel Obtained by Thermo-Reactive Diffusion Technique

In this study, chromium carbide coating obtained by thermo-reactive diffusion (TRD) process on AISI 52100 steel, prepared by packed method at temperature of 850 °C for 2, 4, 6 and 8 h, were investigated by performing a series of tests. The chromium carbide coating was characterized by scanning electron microscopy, X-ray diffraction (XRD), Micro-Vickers hardness test and Daimler-Benz Rockwell-C adhesion test. The chromium carbide layer produced on the AISI52100 steel exhibited a smooth and flat morphology. Depending on treatment time, the coating had a thickness of 3.2 – 8.5 μm. XRD analysis revealed the existence of Cr7C3 and (Cr,Fe)7C3 compounds. The hardness of the surface was increased from 723 to 1730 – 1920 HV0.025 after the coating process. The adhesion strength quality of the coating is correlated to HF2 to HF3 according to the VDI 3198 norm. Comparision of wear performance between chromium carbide coating and substrate showed that the coating can significantly improve wear resistance of the material. Friction coefficient decreased from the 0.46 to 0.37 and wear weight loss decreased by 89.3 %.

Growth kinetics and mechanical characterization of boride layers formed on β-type Ti-45Nb alloy

In this study, β-type Ti-45Nb alloy was borided by solid-state diffusion process in order to achieve a hard and adhered boride layer. Boriding was carried out in a solid medium consisting of amorphous boron, anhydrous borax and active carbon at temperatures between 850 and 1100 °C for time intervals of 3–24 h in order to determine boron diffusion kinetic and to achieve an optimum adhered layer thickness. Microstructure, mechanical properties, adhesion characteristic and growth kinetic of borided layers were investigated in detail by X-ray diffraction, GDOES and SEM-EDS analysis, microhardness and Rockwell-C adhesion tests. A layer consisting of monolithic TiB2·NbB2 phase with the hardness of about 34.3 GPa on the top and TiB whisker with the hardness of about 14.7 GPa beneath it was formed by boriding using optimum processing parameters. A diffusion model based on mass balance equations was used to estimate boron diffusion coefficients and activation energies in the boride layers. Activation energies in TiB2·NbB2 and TiB layers were determined to be 203.96 ± 2.4 kJ/mol and 138.33 ± 24.5 kJ/mol, respectively. Fracture toughness of the borided layer formed at 1000 °C for 24 h was found to be 2.84 ± 0.8 MPa m1/2. Multiple concentric cracks occurred at the peripheral zone of indent by Rockwell-C adhesion test. But no or very limited delamination or spalling occurred due to the result of deeper penetration of TiB whiskers.

Kinetic Investigation and Wear Properties of Fe2B Layers on AISI 12L14 Steel

In the current study, the powder-pack boriding was applied to the AISI 12L14 steel in the temperature range 1123 K to 1273 K for an exposure time between 2 and 8 hours. The produced boride layer was composed of Fe2B with a sawtooth morphology. A diffusion model based on the integral method was applied to investigate the growth kinetics of Fe2B layers. As a main result, the boron diffusion coefficients in Fe2B were estimated by considering the principle of mass balance at the (Fe2B/substrate) interface with an inclusion of boride incubation times. The value of activation energy for boron diffusion in AISI 12L14 steel was estimated as 165 kJ mol−1 and compared with other values of activation energy found in the literature. An experimental validation of the present model was made by using four different boriding conditions. Furthermore, the Rockwell-C adhesion test was employed to assess the cohesion of boride layers to the base metal. The scratch and pin-on-disc tests were also carried out to analyze the effect of boriding on wear behavior of AISI 12L14 steel.