Thermo-reactive Deposition Research Articles

Wear Performance of TiCN Coating on Medium-Carbon Steel by Composite Thermo-Reactive Deposition

Wear Performance of TiCN Coating on Medium-Carbon Steel by Composite Thermo-Reactive Deposition

Growth and mechanical properties of Nb[sbnd]Cr carbide coatings on graphite by TRD technique

Niobium‑chromium (NbCr) carbide coatings were deposited on graphite using the thermo-reactive deposition and diffusion (TRD) technique. The microstructure, hardness, and coefficient of thermal expansion were characterized to search for the optimal treatment parameters for hard and adherent coatings on graphite. The growth rate increased with treatment temperature for fixed treatment duration and remained constant at a constant temperature for about 6 h. The coatings were found to consist of alternating Nb and Cr layers, and this interesting multilayer structure might be explained by the thermodynamics of oxide reduction and carbide formation reactions. Compared to the single-carbides layer, the hardness of the complex coatings increased from about 2500 HV to above 3000 HV, and displayed a smaller gradient of the depth-dependent hardness from the coating to the substrate. The variation of coefficient of thermal expansion of the samples with temperature was similar to that of the graphite substrate at temperatures from 40 to 450 °C. These results showed the effectiveness of the TRD method for synthesizing hard and adherent carbide coatings on graphite, and for other coating/substrate systems with sharply dissimilar mechanical properties.

Production and Characterization of Boride and Carbide Layers on AISI 15B30 Steel

Carbon-boron steels are widely used as components in ground engaging tools and agriculture components, being subject to different forms of tribological wear. The use of treatments to produce hard layers and wear resistance can significantly increase the time to failure and reduce operating costs. In this work, boriding and thermo-reactive deposition (TRD) treatments for the production of boride and carbide layers were performed on the substrates of AISI 15B30 steel to improve tribological characteristics of the surface. The compound phases present in the layers and properties such as hardness, adhesive wear resistance, and layer adhesion were characterized by optical microscope, x-ray diffraction, Knoop microhardness, microadhesive wear test and Rockwell C indentation adhesion according to VDI 3198. The results showed layers with high hardness (1400-2500 HK), greater microadhesive wear resistance (between approximately 10 and 14 times higher than the substrate) and excellent delamination resistance.

Wear Resistance of Niobium Carbide Layers Produced on Gray Cast Iron by Thermoreactive Treatments

Gray cast iron is commonly used due to its high damping capacity, machinability and low cost, due to the presence of free graphite and the high fluidity of the molten metal which facilitates the casting of complex parts with thin walls. Suitable coatings can increase gray cast iron wear resistance and expand its usage range. The high hardness of niobium carbide indicates that it may be a good candidate for this purpose. In this work, samples of gray cast iron with composition 3.47% C-2.39% Si-0.55% Mn-0.15% Ni-0.65% Cu-balance Fe were subjected to two thermoreactive niobizing treatments. The first process (a pack treatment) utilized a powder mixture composed of iron niobium, NH4Cl, Al2O3 at 900 °C during 2 h. The second treatment, a thermoreactive deposition process (TRD), utilized a liquid molten bath of sodium borate and iron niobium performed at 900 °C for 2 h. X-ray diffraction (XRD), Vickers hardness, micro-adhesive (fixed-ball) and micro-abrasive (free-ball) wear tests were used to characterize the treated samples. Hardness layers of 2000 HV, typical for niobium carbides, were obtained. Wear tests demonstrated a substantial increase (2 to 12 times higher than that the substrate) in wear resistance obtained with niobizing treatments.

Characteristics of Products of Thermo Reactive Deposition Surface Treatment on JIS-SUJ2 Steel using Fe-Cr Coating Powder with Process Temperature Variation

In this study the effect of temperature variation of the thermo-reactive deposition (TRD) process on carbide layer formation on SUJ2 steel substrates by pack cementation using Ferrochromium powder as carbide former was studied. This process was carried out on SUJ2 steel substrates at temperatures of 900, 980 and 1060 °C for 6 hours. The effect of temperature on layer thickness, homogenity and hardness was studied. Results show that the higher the temperature the thicker the layer formed on the substrate surfaces. Furthermore the XRD results show that the layer formed by this process is chromium carbide. The average microhardness of the layer for 3 process temperature variations is around 1750 HV while the wear rate is around 7 x 10−4 mm3/m.

Effect of FeV Residual Powders as an Innovation of Thermo Reactive Deposition Process (TRD) with Material Balance Method to Carbide Surface Characteristics on SUJ2 Tool Steel

Thermal Reactive Deposition (TRD) using pack cementation method with vanadium as carbide former has been examined to form the carbide layer on SUJ2 tool steel. In this study, effect of addition recycled FeV powder to new FeV powder to the product quality. Calculation analysis resulted 4 variations of FeV powder ratio to be studied i.e. 100% new FeV powder; 100% residual FeV powder; new powder FeV : residual FeV powder 50%:50%; New FeV powder : residual FeV powder 25%:75%. Electron microscope (SEM) and optical microscope (OM) analysis showed that the carbide layer formed in each sample had the same relative layer thickness of about 18μ. X-ray diffraction (XRD) characterized showing that there were a vanadium carbide compound in the formed layer. Hardness test and wear test resulted a relatively similar hardness value of about 1800 HV and 3×10−5 mm3/m. It can be concluded that the use of residual FeV powder to the new FeV powder can be applied because the test results with various ratios that have been done have relatively similar results and meet the hardness application specification of 1700 HV.

Wear and Corrosion Resistance of Chromium–Vanadium Carbide Coatings Produced via Thermo-Reactive Deposition

Chromium carbide, vanadium carbide, and chromium–vanadium mixture coatings were deposited on AISI D2 steel via the thermo-reactive deposition/diffusion (TRD) technique. The carbides were obtained from a salt bath composed of molten borax, ferro-chrome, ferro-vanadium, and aluminum at 1020 °C for 4 h. Analysis of the morphology and microstructure of the coatings was done via scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The hardness of the coatings was evaluated using nano-indentation, and the friction coefficient was determined via pin-on-disk (POD) testing. The electrochemical behavior was studied through potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS). The XRD results show evidence of the presence of V8C7 in the vanadium carbide coating and Cr23C6 and Cr7C3 in the chromium carbide coating. The hardness value for the vanadium–chromium carbide coating was 23 GPa, which was higher than the 6.70 ± 0.28 GPa for the uncoated steel. The wear and corrosion resistance obtained was higher for the niobium–chromium carbide coating, due to the nature of the ceramic carbide produced.

Effect of FeCr/FeV Ratio During Thermo-Reactive Deposition(TRD) Process on Mechanical Properties and Characteristics of Carbide Layer of SUJ2 Steel

Abstract Pack thermo-reactive deposition (TRD) process has been carried out on SUJ2 (AISI 52100) steel substrate, with different wt.% ratio of FeCr/FeV coating powder. In general, TRD process is able to produce several types of hard layer, e.g. carbide, nitride, or carbonitride layer to improve steel surface hardness and wear resistance. In this work, the FeCr/FeV coating powder ratio used were 15/85, 36/65, and 50/50 wt.%. The TRD process temperature was set at 980°C and held for 6 hours. Characterization was performed using microhardness tester, optical microscope and X-ray diffraction (XRD). The characterization results showed that the higher FeV ratio, the higher the hardness and the thicker the layer. The layer thicknesses of 17, 24.1, and 24.6 μm with the average microhardness value was 1989, 2148, and 2296 HV, for 50%, 65% and 85% FeV ratio, respectively. Similar with the hardness result, the lowest wear rate at 3.4x10-4 mm3/m was obtained at 15FeCr/85FeV wt.% ratio. XRD identification showed that mixing the FeCr and FeV powder was successfully producing vanadium. chromium, and complex carbide layer on the surface of steel substrate. Several possible phases that formed in the layer were. V6C5, V8C7, Cr7C3, Cr3C6, VCr2C2, and Cr2Fe14C.

Multilayer-Forming Behavior of Cr Nitrides and Carbides for Thermoreactive Deposition

The effect of a nitride layer on the forming behavior of CrN and (Cr, Fe)7C3 multilayers for thermoreactive deposition (TRD) was investigated. Plasma nitriding followed by TRD (PN-TRD) produced a larger coating thickness than the case of direct TRD with no plasma nitriding. For PN-TRD, an Fe2-3N layer of 10 μm in thickness was produced on AISI 52100 steels using plasma nitriding, followed by TRD using a mixed powder composed of 30 wt % Cr, 2 wt % NH4Cl, and 68 wt % Al2O3. During TRD at 800 °C, a CrN layer of 2 μm in thickness was formed along with a thin layer of mixed carbide (Cr7C3) and nitride (CrN) on top. As the deposition temperature was increased to 950 °C, a new layer of Cr7C3 was formed underneath the outermost layer composed of mixed Cr7C3 and CrN. At 950 °C, a Cr-rich zone indicated a thickness of ~7 μm. As the deposition time increased to 3 h at 950 °C, a new layer of (Cr, Fe)7C3 was produced at the interface between the CrN formed at 800 °C and the base metal. This layer formed because of the abundant resources of Cr and C provided from the TRD powder and base metal, respectively. The multilayer and interface were concretely filled without the formation of voids as the TRD time increased to 6 h at 950 °C. The TRD process on a pre-nitrided layer was successfully applied to produce multilayers of CrN and Cr7C3.

Growth behavior and mechanical properties of Cr-V composite surface layer on AISI D3 steel by thermal reactive deposition

The growth dynamics of hard Cr-V composite surface layer on AISI D3 cold work steel surface was investigated, where the coating was fabricated by Thermo-reactive deposition at 1000 °C. The heating durations critically contributes to the microstructure evolution as well as the coating adhesive strength and mechanical properties. Surface and interface structural changes were observed by Scanning Electron Microscopy, Energy Dispersive X-ray spectroscopy, and X-ray diffraction. The results well show, the growth of Cr-V composite layer depends on the coating process duration, the thickness of obtained coatings ranged from 5.0 to 11.8 μm. The obtained coating demonstrates the multilayered structure consisting of the carbide located at the outmost layer and diffusion layer of Fe-Cr solid solution. The coating demonstrates desirable adhesive strength and toughness. A possible growing model of formation process for the Cr-V composite surface layer was proposed.

Surface and corrosion properties of modified passive layer on 304 stainless steel as bipolar plates for PEMFCs

In this study, the relation between surface chemistry and corrosion properties of modified 304 stainless steels (304SS) was investigated. 304SS samples were submitted to plasma nitriding performed at two different temperatures: 420 °C (low) and 520 °C (high). Then, a thermo reactive deposition (TRD) was used in a mixture of ferro niobium, alumina and ammonium chloride. Finally, a pickling treatment was performed to access high corrosion resistant surfaces. Surface treated samples, both before and after pickling, were investigated by using Scanning Electron Microscopy (SEM) and Potentiodynamic (PD) techniques. X-ray Photoelectron Spectroscopy (XPS) was performed for the analysis of the surface layers of the samples after pickling.The surface layers were mostly comprised of iron and chromium oxides and hydroxides. XPS results proved the presence of a surface layer mostly constituted by iron oxides and oxyhydroxides for both the treated samples that resulted more homogenous for the sample nitrided at low temperature. Chromium was detected by XPS in the predominant form of oxide on the surface of the sample nitrided at low temperature.

Hard Surface Layers by Pack Boriding and Gaseous Thermo-Reactive Deposition and Diffusion Treatments

Abstract Thermo-reactive deposition and diffusion (TRD) and boriding are thermochemical processes that result in very high surface hardness by conversion of the surface into carbides/nitrides and borides, respectively. These treatments offer significant advantages in terms of hardness, adhesion, tribo-oxidation, and high wear resistance compared to other conventional surface hardening treatments. In this work, 4 different materials, ARMCO, AISI 409, Uddeholm ARNE® (AISI O1 equivalent), and VANADIS® 6 PM steel representing different classes of alloys, i.e., pure iron, stainless steel, and tool steels, were subjected to TRD (chromizing and titanizing) and boriding treatments. For the steels with low carbon content, chromizing results in surface alloying with chromium, i.e., formation of a (soft) “stainless” surface zone. Steels containing higher levels of carbon form chromium carbide (viz. Cr23C6, Cr7C3) layers with hardnesses up to 1800 HV. Titanizing of ARNE tool steel results in a surface layer consisting of TiC with a hardness of approximately 4000 HV. Duplex treatments, where boriding is combined with subsequent (TRD) titanizing, result in formation of hard TiB2 on top of a thick layer of Fe-based borides. The obtained surface layers were characterized with X-ray diffraction, scanning electron microscopy, reflected light microscopy, and micro-indentation.

Properties of the Functionally Gradient Chromium-Niobium Carbide Coating Obtained by Thermo-Reactive Deposition Technique

Thermo-reactive deposition (TRD) salt bath Nb-Cr co-diffusion process was brought forward to prepare the functionally gradient chromium-niobium carbide coating. In TRD salt bath Nb-Cr co-diffusion treatment, T10 steel samples were delved into TRD salt. The samples were treated at 880°C for 3.5 h and then at 950°C for 2.5h. The obtained coatings were characterized by means of microstructure, microhardness, scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) and X-ray diffraction analysis (XRD). The cross-section hardness of the chromium-niobium carbide coating obtained on the surface of T10 steel samples transits smoothly. The coating was dense, smooth and compact. The thickness ratio of the niobium carbide layer (the outer layer) and the chromium carbide layer (the inner layer) was 4. The hardness of chromium-niobium carbide coating was about 2751HV0.05, which is between the single chromizing and single niobium. The results showed superior wear properties of the coated samples. The kinetics of chromium-niobium carbide coating was also studied.

Surface modification of 304 stainless steels to improve corrosion behavior and interfacial contact resistance of bipolar plates

In this study, plasma nitrided stainless steel (SS304) at low and high temperature, treated by Thermo Reactive Deposition (TRD) and then pickled is investigated under PEMFC accelerated condition. Surface characterization is performed by SEM, EDS, XRD, AFM, and GD-OES. Potentiostatic (PS) and electrochemical impedance spectroscopy (EIS) is used to assess corrosion resistance of untreated and treated samples. Interfacial contact resistance (ICR) measurements are carried out to investigate the surface conductivity. The results reveal that TRD treated samples are covered by an inhomogeneous layer that cannot protect the substrate. Corrosion resistance and conductivity of pickled samples improve significantly. The improvements are attributed to a rich chromium layer and the low roughness of the modified passive layer. A bi-layer (outer porous and inner dense layer) structure is proposed as the most appropriate model for the passive film. Contact angle measurements indicate improved hydrophobicity of pickled samples.

Effect of Aluminum Addition to Nb-Al-C-N Coatings on AISI M2 Steel Obtained by Thermo-Reactive Deposition Technique

In this study, aluminum-doped (1 and 2 wt.%) and Al-free niobium carbo-nitride coatings were applied to the surface of AISI M2 high speed steel using the process of thermo-reactive deposition technique (TRD) at 1000 ◦C during 1–4 h. The obtained coatings were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) analysis and micro hardness test. Nb-Al-C-N layers were compact and homogeneous. X-ray diffraction analysis has shown that the major phases formed in the coating layer are Nb2CN and NbN. The depth of the coating layer had increased with the treatment time and ranged from 6.65 to 9.05 μm. The measured values of the hardness of the coating layers were ranging between 2136 and 2636 HK0.005.

Wear and corrosion of niobium carbide coated AISI 52100 bearing steel

Bearing steels must have high hardness, good wear resistance and dimensional stability. In the present work, the AISI 52100 bearing steel was selected as the substrate for a niobium carbide coating produced by a salt-bath thermo-reactive deposition process. The present work addresses the effect of niobium carbide coating on the wear and corrosion resistance of the abovementioned steel. A homogeneous layer composed solely by the cubic niobium carbide (NbC) was produced. The carbide coating yielded average hardness and elastic modulus of 26GPa and 361GPa, respectively. No significant decarburization was detected beneath the case by means of hardness fluctuations. Dry wear tests resulted in worn volumes 10 times smaller for the NbC coated steel, comparatively to the untreated substrate, at three different applied loads. Corrosion tests in NaCl solution indicated an improved behavior for the carbide coated bearing steel at applied potentials inferior than 250mV. At higher potentials, the electrolyte appears to penetrate trough the layer yielding wide corrosion caps.

Duplex ceramic coating produced by low temperature thermo-reactive deposition and diffusion on the cold work tool steel substrate: Thermodynamics, kinetics and modeling

Specimens of DIN 100MnCrW4 steel (type O1 tool steel) have been cut and prepared for performing a duplex surface treatment involving nitriding and low temperature vanadium thermo-reactive deposition and diffusion (TRD) technique. The TRD process was performed in a molten salt bath at different temperatures of 575, 650 and 725°C for 1–30h. The treatment formed a vanadium carbonitride coating with the thickness up to 10.5μm on a hardened diffusion zone. Characterizations by means of an optical microscope (OM), scanning electron microscope equipped with energy dispersive X-ray spectrometer (SEM–EDS) and X-ray diffraction analysis (XRD) indicated that the compact and dense coating mainly consisted of V(C,N) and V2(C,N) phases. All the growth processes of the formed vanadium carbonitride layer obtained by TRD followed a parabolic kinetics while the calculated activation energy (Q) for the treatment was 181.1kJ/mol. An artificial neural network (ANN) based model for predicting the layer thickness of ceramic coatings was presented. Constructing the model, training, validating and testing of experimental results from 72 different specimens were conducted. The data used as inputs in the proposed model were arranged in a format of five parameters that comprised of “pre-nitriding time”, “ferro-vanadium particle size”, “ferro-vanadium weight percent”, “salt bath temperature” and “coating time”. Accordingly, the thickness of duplex coating in each specimen was estimated accurately. Finally, the proposed ANN-based model showed a strong potential for predicting the layer thickness of duplex ceramic coating performed by the TRD technique on the substrate of cold work tool steel.

Evaluación tribológica de recubrimientos de nbc y VC sobre acero AISI D2 producidos por la técnica deposición difusión termo-reactiva

In this work vanadium carbides (VC) and niobium carbide (NbC) coatings were produced on AISI D2 tool steels system using the thermo reactive deposition diffusion technique (TRD). The experiments were performed in a salt bath (borax) with dissolution of ferro-niobium, ferro-vanadium and aluminium at temperature treatment of 1000°C during 3hours. The coatings obtained were characterized by scanning electron microscopy and X-ray diffraction. The tribological behavior was studied by the technique of pin on disc to define the coefficient of friction and scratch technique to determine the adhesion level. Results were compared with uncoated substrates, a decrease of the friction coefficient and an increase in the hardness was observed.

Structural Characterization of Boro-Titanized AISI 1040 Steel

In this study, boro-titanizing treatment was applied to AISI 1040 steel. In the coating treatment, steel samples were pre-boronized in a slurry salt bath consisting of borax, boric acid and ferro-silicon at 900 ◦C for 2 h, then titanized by thermo-reactive deposition technique (TRD) in a powder mixture consisting of ferro-titanium, ammonium chloride, alumina and naphthalene at 1000 ◦C for 1 4 h. The coated samples were characterized by Xray di raction analysis (XRD), scanning electron microscope (SEM), glow discharge optical emission spectroscopy (GDOES) and micro-hardness tests. Coated layer formed on the pre-boronized AISI 1040 steel was compact and homogeneous. X-ray studies showed that the phases formed on the steel surfaces are TiB2, TiC, TiN and Fe2B. The depth of the coating layer ranged from 3.41 ± 0.47 μm to 6.59 ± 0.51 μm, depending on treatment time. A higher treatment time resulted in a thicker boro-titanized layer. The average hardness of the coating layer was 4527± 284 HV0.005.

Modeling layer thickness of duplex ceramic (chromium carbonitride) coating on cold work tool steel using fuzzy logic

The paper presents some results of the research connected with the development of new approach based on the fuzzy logic FL of predicting the layer thickness of the chromium carbonitride CrC,N in 1.2210 steel after thermoreactive deposition and diffusion TRD coating. The independent variables in the model are nitriding time, salt bath compositions ratio, salt bath aging time, ferro-chromium particle size, ferro-chromium weight percent, salt bath temperature and coating time. The model output variable was the layer thickness of coating. For purpose of constructing these models, 105 different experimental data were gathered from the experiment. The data used in the fuzzy logic model is arranged in a format of eigth parameters that cover the input and output parameter. In this model, the training and testing results in the fuzzy logic systems have shown strong potential for prediction of effects of pre-nitriding, salt bath condition and coating variables on layer thickness of CrC,N coating on 1.2210 steel.