Cold Spray Method Research Articles

Improving bond strength and deposition efficiency of ceramic coatings via low pressure cold spraying: A study on hydroxyapatite coatings with Cu-Zn blends

This study presents Low Pressure Cold Spraying (LPCS) method for ceramic coatings, aimed at enhancing efficiency and elucidating bonding mechanisms. It focuses on the deposition of ceramic coatings using LPCS, with hydroxyapatite (HA) on 316L stainless steel (SS) as an illustrative example. Despite the advantages of LPCS, retaining HA particles has proven challenging, resulting in thin coatings (11.09 ± 2.56 μm) with low bonding strength (1.80 ± 0.19 MPa). To address this issue, a composite coating strategy was developed by blending 20 wt% Cu and Zn powder with 80 wt% HA. This approach significantly improved coating properties, achieving enhanced bonding strength (33.70 ± 1.13 MPa), deposition efficiency (27 %), and hardness (136.30 ± 2.45 HV) compared to pure Cu-Zn coatings. Numerical simulations were conducted to interpret these experimental results, indicating that blending metal with HA improves deposition efficiency, bonding strength, and hardness. In HA coatings, particles fragment into submicron grains and embed into the substrate through mechanical interlocking (MI), with shockwave-induced bonding strengthening subsequent layers. For Cu-Zn coatings, bonding occurs through MI and adiabatic shear instability (ASI). In HA-Cu-Zn coatings, high-velocity HA particles and Zn particles enhance bonding further through in-situ tamping.

Constructing carbon nanotube (CNTs)/silica superhydrophobic coating with multi-stage rough structure for long-term anti-corrosion and low-temperature anti-icing in the marine environment

The rough superhydrophobic surface is beneficial for capturing more gases underwater, which enhances corrosion and ice resistance for marine equipment. In this work, a PVAc-PVDF-FMCS (PPFMCS) multi-stage rough superhydrophobic coating was manufactured by a cold spraying method, significantly improving the anti-corrosion and anti-icing of aluminium alloy. The point-line structure was designed by cross-linking between multi-walled carbon nanotubes (MWCNTs) and silicon dioxide (SiO2), which facilitated the formation of multi-stage rough surface. The porous skeleton and interfacial adhesion of the PPFMCS coating were attributed to the introduction of polyvinylidenefluoride (PVDF) and polyvinylacetate (PVAc), respectively. The PPFMCS coating had good superhydrophobicity with a water contact angle of 163.5°, while exhibiting the outstanding performance of long-term anti-corrosion and anti-icing. The |Z|0.01 Hz value of the PPFMCS coating was still 9.62 × 109 Ω cm2 in 3.5 wt% NaCl solution for 35 days, only two orders of magnitude lower than that of the original coating, the equivalent circuits were further investigated and the metal protection is evaluated on the shore or in the deep ocean of the South China Sea. The PPFMCS coating was able to obviously delay icing for 5 min at −20 °C, the ice adhesion of its surface was as low as 85.5 kPa. The icing phase transition was analysed by a thermodynamic method. The coating also had good stability and drag reduction performance. This high-performance coating based on point-line structural design is expected to have practical applications in marine transportation, oil exploration and polar exploration.

CAVITATION EROSION BEHAVIOR OF WC–Co COATINGS ON TURBINE STEEL DEPOSITED BY COLD SPRAY

A renowned hard coating material (WC–Co) has the potential to overcome cavitation erosion (CE) in hydromachinery components. Hydro turbines that employ silt-filled water for electricity generation create a lot of metal waste due to erosion and cavitation caused by the particles. There is an urgent need for repair of hydropower components that have undergone damage due to cavitation. In this investigation, tungsten carbide composite coatings were produced on 13Cr4Ni (CA6NM) stainless steel substrates using the cold spray method. In order to create high-quality coatings, nitrogen was used as the propellant gas. The coating microstructures were characterized by EDS, SEM XRD, and microhardness tests. Cold-sprayed WC–Co-based coatings were exposed to enhance the cavitation erosion resistance of CA6NM steel. Cold spray coating prepared with WC-12/17Co powder has shown excellent wear-resistant properties due to higher hardness and lower porosity.

Repairing Al7075 surface using cold spray technology with different metal/ceramic powders

Cold spray process is essentially a coating technique as well as used in repair applications. This method is a low-temperature solid-state process. In this study, the damaged surface of Al7075 was repaired by low pressure cold spray method with Ni-Zn-Al2O3, Al-Zn-Al2O3, Al-Al2O3, Ni-Al2O3, and Zn-Al2O3 metal/ceramic feedstock powders. Microstructure examination, microhardness measurements, tribological experiments, and tensile tests were conducted on the repaired samples and compared with Al7075. The repaired regions exhibited a composite microstructure characterized by the presence of Al2O3 ceramic particles with high hardness dispersed within a metal matrix composed of Al, Ni, Zn, Ni-Zn, and Al-Zn. This composite structure was attributed to the interlocking mechanism of cold spray. The highest hardness value was measured in the repaired area using Ni-Al2O3, which is approximately 1.28 times higher than that of Al7075 alloy. According to the dry sliding test, the wear performance of all repaired specimens was superior to that of Al7075. The wear resistance of samples repaired with Ni-Al2O3 and Ni-Zn-Al2O3 increased approximately 7.1 and 5.8 times, respectively, compared to Al7075. The specimens repaired with Ni-Zn-Al2O3 feedstock powder showed the most similar results in tensile and yield strength values to Al7075 to the tensile test.

Cold Spray Deposition of MoS2- and WS2-Based Solid Lubricant Coatings

The cold spray deposition technique has been used to produce a new class of solid lubricant coatings using powder feedstocks of the metal disulfides WS2 or MoS2, either pure or mixed with Cu and Ni metal powders. Friction and cycle lives were obtained using ball-on-flat reciprocating tribometry of coated 304 SS flats in dry nitrogen and vacuum at higher Hertzian contact stresses (Smax = 1386 MPa (201 ksi)). The measured friction and thickness of the coatings were much lower than for previous studies (COF = 0.03 ± 0.01 and ≤1 µm, respectively), which is due to their high metal disulfide:metal ratios. Cu-containing metal sulfide coatings exhibited somewhat higher cycle lifetimes than the pure metal sulfide coatings, even though the Cu content was only ~1 wt%. Profiling of wear tracks for coatings tested to 3000 cycles (i.e., pre-failure) yielded specific wear rates in the range 3–7 × 10−6 mm3N−1m−1, similar to other solid lubricant coatings. When compared to other coating techniques, the cold spray method represents a niche that has heretofore been vacant. In particular, it will be useful in many precision ball-bearing applications that require higher throughput and lower costs than sputter-deposited MoS2-based coatings.

DEPENDENCE OF MICROHARDNESS OF ASD-1 COATINGS ON COLD SPRAYING PROCESS PARAMETERS

Purpose. To investigate the effect of the main parameters of the cold spraying process, particularly the temperature and pressure of the gas at the nozzle inlet and stand-off distance, on the microhardness of the ASD-1 aluminum coating. Research methods. The planning and conducting of experimental research were carried out using the design of experiment methodology and regression analysis. The analysis of the obtained results of the experiments was carried out in the software package for statistical data Stat-Ease 360. The research of the microhardness of the sprayed coatings was carried out following GOST 9450-76 “Measurements microhardness by diamond instruments indentation@ using a LECO AMH5 micro-Vickers hardness tester on the prepared cross-section of samples with coatings. Results. Three-dimensional (response surfaces) and contour graphs of the dependence of the microhardness of coatings deposited by the cold spraying method from ASD-1 powder on the main process parameters - the temperature and pressure of the gas at the nozzle inlet and stand-off distance in a wide range of values - were constructed. According to the results, it was established that the gas temperature and the spraying distance have the most significant influence on the microhardness of the coatings. The relationship between the investigated parameters of spraying with the temperature and velocity characteristics of the powder particles and their effect on the microhardness is described. Scientific novelty. The complex effect of the main parameters of the cold spraying process, particularly the temperature and gas pressure at the nozzle inlet and the stand-off distance, on the microhardness of ASD-1 aluminum coatings in a wide range of values, was investigated. Practical value. The obtained dependences of coating microhardness on process parameters can be used in developing scientifically-based recommendations and technological processes of deposition of protective and restorative coatings by cold spraying, particularly on parts of aircraft engines.

The Comparative Effectiveness of Using Cold Water Oral Spray and Cold Saline Oral Spray for Thirst Relief in Patients With Endotracheal Intubation in the Intensive Care Unit

Thirst is a common symptom among patients with endotracheal intubation in the intensive care unit (ICU), with an estimated prevalence of 88%. This study was designed to compare the effectiveness of cold saline spray and cold water spray in alleviating thirst, and to explore the maintenance and sustained effects of both groups in relieving thirst among patients with endotracheal intubation in the ICU. Patients with indwelling tracheal tubes in the medical ICU were recruited from one medical center in northern Taiwan and randomly assigned to either the cold saline (n = 18) or cold water (n = 18) group. The cold saline group received three rounds of cold saline spray at a temperature of 2°C - 8°C. Each round consisted of 10 sprays directed toward each of the four surfaces of the oral cavity followed by a 5-minute wait period. This process was repeated three times, with 30-minute intervals between interventions. The cold water group received the same intervention steps using a cold water spray at 2°C - 8°C. Thirst intensity was measured using a numeric rating scale before and after each of the three interventions in both groups. Demographic and relevant physiological data were collected on the participants by reviewing their medical records. Both of the interventions were found to effectively alleviate thirst intensity, with no significant difference between the two groups in terms of thirst intensity reduction after each intervention detected. Only the cold water spray had a maintenance effect, while the two groups had a continuous sustained effect in alleviating thirst intensity. Both of the interventions effectively alleviated thirst, and the cold water spray had both maintenance and sustained effects in alleviating thirst intensity. Based on the results, the cold water spray method may be considered as the priority treatment for thirst alleviation by healthcare providers in the clinical management of patients with tracheal intubation.

Enhanced Pool Boiling Heat Transfer with Porous Ti-6Al-4V-Coatings Produced by Cold Spray Metal Additive Manufacturing

In advancing industrial heat transfer mechanisms, surface coatings offer significant potential. This research elucidates the efficacy of the metal additive manufacturing Cold Spray deposition technique for producing enhanced boiling surfaces, specifically focusing on Ti-6Al-4V (Ti64) coatings on Aluminium substrates. This offers a rapid and low-cost fabrication method for producing lightweight enhanced boiling surfaces. The Cold Spray method is typically used to create dense metal deposits. Here, the process has been specially tuned to create highly inhomogeneous honeycomb-type porous Ti64 coatings. Critical Cold Spray deposition parameters, such as particle velocity, preheat temperature, and deposition rate have been identified to create repeatable porous coatings, with thicknesses of up to 3.0 mm achievable. Following deposition, several samples were subjected to systematic boiling heat transfer tests in a purpose-built pool boiling apparatus. Boiling curves were generated for the augmented Cold Spray surfaces as well as a bare surface, with the latter acting as a baseline to which enhancement levels were assessed. Initial data analysis shows that some of the tested surfaces exhibit a notable increase in boiling heat transfer coefficient and Critical Heat Flux (CHF). This enhancement is potentially attributed to increased surface area, increased nucleation site density, capillary wicking, and mitigation of lateral bubble coalescence, though excessive coating thickness may degrade heat transfer. In summary, the novel Ti64 surface structures developed using the Cold Spray deposition technique exhibits high potential for industries necessitating superior boiling heat transfer performance. Importantly, the manufacturing process is industrially scalable, offering the capacity to rapidly coat large areas at low cost compared with subtractive manufacturing other metal additive manufacturing methods.

Effects of tetramethylpyrazine on pharmacokinetics in plasma and brain dialysate and neuropathic pain in rat model of spared sciatic nerve injury

This study aims to explore the effects of tetramethylpyrazine(TMP) on pharmacokinetics in plasma and brain dialysate and neuropathic pain in the rat model of partial sciatic nerve injury(SNI), and to investigate the correlation between the analgesic effect of TMP and its concentrations in the plasma and brain dialysate. Male SD rats were randomized into Sham, SNI, and SNI+TMP groups. Mechanical stimulation with von frey filaments and cold spray method were employed to evaluate the mechanical sensitivity and cold sensitivity of rats. Another two groups, Sham+TMP and SNI+TMP, were used to intubate the common jugular vein and implant microdialysis probes into the anterior cingulate gyrus(ACC), respectively.After intraperitoneal injection of TMP at a dose of 80 mg·kg~(-1), automatic blood collection and intracerebral microdialysis(perfusion rate of 1 μL·min~(-1)) systems were used to collect the blood and brain dialysate for 24 h. HSS T3 C_(18) reversed-phase chromatographic column(2.1 mm×50 mm, 2.5 μm) was used for liquid chromatographic separation. Gradient elution was carried out with the mobile phase of methanol-water(containing 0.005% formic acid) at a flow rate of 0.25 mL·min~(-1). Electrospray ion source was used for mass spectrometry, and the scanning mode was multi-reaction monitoring under the positive ion mode. The ion pairs for quantitative analysis were TMP m/z 137/122 and aspirin m/z 179/137, respectively. DAS 2.11 was used to calculate the pharmacokinetic parameters. The optimal time of TMP to exert the analgesia effect and inhibit cold pain sensitivity was 60 min after treatment. The TMP in the plasma and brain dialysate of SNI rats showed the T_(max) of 15 min and 30 min, the C_(max) of(2 866.43±135.39) and(1 462.14±197.38) μg·L~(-1), the AUC_(0-t) of(241 463.30±28 070.31) and(213 115.62±32 570.07) μg·min·L~(-1), the MRT_(0-t) of(353.13±47.73) and(172.16±12.72) min, and the CL_Z of 0.73 and 0.36 L·min·kg~(-1), respectively. The analgesic effect of TMP had a significant correlation with the blood drug concentration in the ACC, which indicated that this method was suitable for the detection of TMP in rat plasma and brain dialysate. The method is accurate, reliable, and sensitive and can realize the important value of the application of correlation analysis theory of "automatic blood collection-microdialysis/PK-PD" in the research on neuropathic pain.

Microstructure and corrosion properties of Cu coatings deposited via laser-assisted low-pressure cold spray

Cu coatings were prepared via the laser-assisted low-pressure cold spray (LPCS) method to study the effect of laser irradiation on microstructure and corrosion behaviors of the coatings. The results reveal that the laser-assisted LPCS-Cu coatings are denser and have better coating−substrate interfacial bonding as compared to LPCS-Cu coating. Laser irradiation improves the overall plastic deformation of deposited particles, resulting in uniform grain refinement of Cu particles. Therefore, the laser-assisted LPCS-Cu coatings show more uniform microstructure and smaller grain size. The results of electrochemical tests demonstrated that laser-assisted LPCS-Cu coatings have higher corrosion potential, lower corrosion current and corrosion rate than the LPCS-Cu coating in 3.5 wt.% NaCl solution. The main reason is that laser irradiation improves the coating density and intimate bonding between particles, and a continuous and dense corrosion product film composed of CuCl and Cu2O is formed on the surface of the laser-assisted LPCS-Cu coating to block the erosion of the corrosive solution.

Investigation of the causes of destruction of materials obtained by the cold spraying method during their operation in vacuum

Investigation of the causes of destruction of materials obtained by the cold spraying method during their operation in vacuum

Deposition of Al Coatings by Cold Spray Method on AZ91 Mg Alloy

Hafif metalik mühendislik malzemelerinden biri olan AZ91 magnezyum alaşımı; sahip olduğu düşük yoğunluk ve yüksek özgül mukavemet özelliklerinden dolayı endüstrinin birçok alanında yapı malzemesi olarak tercih edilmektedir. Ancak AZ91 alaşımının sahip olduğu güçlü yapısal özelliklerine rağmen yüzey özelliklerinin sınırlı olması, saldırgan ortamlarda ve aşırı yük altında düşük dayanıma sahip olmasına dolayısıyla bu alaşımların kullanımlarının sınırlı kalmasına neden olmaktadır. Bu alaşımların zayıf yüzey özelliklerini geliştirmek ve endüstrinin farklı alanlarında kullanımlarını arttırılabilmek için yüzey kaplama işlemleri uygulanabilmektedir. Bu çalışmada; AZ91 magnezyum alaşımının yüzey özelliklerini iyileştirilebilmek amacı ile soğuk sprey (SS) yöntemi ile Al kaplamaların büyütülmesi amaçlanmıştır. Büyütülen kaplamaların yapısal morfolojik analizleri kaplamaların XRD ve SEM analizleri ile sertlik değerleri ise mikro sertlik ölçme yöntemiyle tespit edilmiştir.

Evaluation of a hybrid cold spray and machining method for fabrication of parts with high surface integrity

Cold spray technology has been proven to have various engineering and manufacturing applications, including the capability to restore previously unrepairable parts. However, like most additively manufactured parts, it will likely require post-processing, such as machining, to improve surface finish and dimensional accuracy. In addition, cold spray deposits are typically porous. The porosity may be detrimental to the mechanical performance of the component. This paper presents a systematic evaluation of cold spray using readily available nitrogen as carrier gas, subsequent machining utilizing negative rake angle tools, and the effect of this novel hybrid fabrication method on subsurface porosity. The machining is optimized via finite element analysis (FEA) and the optimum is verified by experiments. The analysis informs the engineering of the proposed hybrid cold spray/machining method.

TRIBOLOGICAL WEAR ANALYSIS OF Ti-Al COMPOSITE COATINGS APPLIED WITH THE COLD SPRAY METHOD

The possibility of using the low-pressure cold gas spraying (LPCS) method to create composite coatings hasbeen known and used for a long time. This method makes it possible to create coatings from physically andchemically different powders and to regenerate components damaged during operation. Composite coatingsof titanium and aluminium at different weight concentrations were selected for the study. The research wasconducted to optimise the influence of the chemical composition of the composite coatings on their tribologicalproperties. This paper presents the results of tribological wear testing of composite coatings applied using thelow-pressure cold gas spray (LPCS) method. Wear resistance tests were performed using the ball-on-platemethod in reciprocating motion using a steel ball. Tribological testing of the coatings included determiningthe effect of contact force on wear and the value of the kinetic coefficient of friction of the friction pairs tested.The study determined the optimum chemical composition of the Ti-Al composite coatings to improve wearproperties.

Microstructure, mechanical properties, and tribological properties of laser assisted cold sprayed CuCrZr coatings: Influences of laser power and laser position

CuCrZr has good conductivity, thermal conductivity and high strength and is widely used in the production of continuous casting mold. In this study, for the first time, high-performance CuCrZr coatings were successfully deposited on the surface of CuCrZr mold by laser assisted cold spray (LACS) method as a preliminary trial to validate LACS a repair technique of worn mold surfaces. This study systematically characterizes the microstructure, microhardness, bonding strength, electrical conductivity, wear performance, and thermal shock performance of CS, concentric LACS and eccentric LACS coatings. The results show that compared to CS, LACS shows great improvements in coating density, bond strength, friction and wear performance, and electrical conductivity, thus exhibiting significant prospects in the repair of mold. In particular, eccentric LACS CuCrZr coatings feature higher bonding strength and deposition efficiency, while concentric LACS coatings have better wear, hardness, and electrical conductivity. The best overall coating performance is achieved at eccentric LACS-4 kW-5.5 mm CuCrZr coating which exhibits a porosity of 0.49 %, a grain size of 1.06 µm, a microhardness of 200 HV0.3, a bond strength of 205 MPa (on CuCrZr substrates), a friction coefficient of 0.48 and a wear rate of 1.55 × 10-5 mm3/N·m (counterbody: GCr15 balls, 15 N load), an electrical conductivity of 63.50 % IACS, and a thermal shock resistance of > 120 cycles under 650 ℃. The mechanisms associated with microstructural formation and mechanical performances of LACS coatings are also analyzed. There was no obvious phase change within the coating, while a heat affected zone is formed at the coating-substrate interface with the formation of CuxZry phases and slight oxides. The grain characteristics of LACS coatings include deformed grains, recovered grains, recrystallized grains. The wear mechanisms of LACS coatings are combined adhesive wear and abrasive wear.

Balanced Anti-Corrosion Action of Reduced Graphene Oxide in Zn-Al Coating during Medium-Term Exposure to NaCl Solution

Considering the electronegativity and shielding anti-sepsis characteristic of reduced graphene oxide (G), we design a Zn-Al coating with embedded G (Zn-G/Al) on low-carbon steel using the low-pressure cold spray (LPCS) method. In this method, G-coated Al powders (G/Al) prepared using in situ reduction and Zn powders were mixed as a raw material for spraying. Embedding G could boost the cathodic protection performance of Zn-Al (70 wt.% zinc and 30 wt.% aluminum) coating, as has been confirmed in previous work. In this work, the microstructure, composition and electrochemical parameters of Zn-G/Al coating during full immersion were measured to investigate G’s effect on the corrosion protection properties of the Zn-Al coating. The test results showed that embedded G could facilitate the generation of many corrosion products and pile on the coating surface to form a corrosion product film during full immersion. The corrosion product film on the Zn-0.2 wt.%G/Al coating surface demonstrated an excellent protective property, which reflects the fact that the Ecorr and icorr values for Zn-0.2 wt.%G/Al after 20d immersion (Ecorr = −1.143 Vvs.SCE, icorr= 49.96 μA/cm2) were lower than the initial value (Ecorr = −1.299 Vvs.SCE, icorr = 82.16 μA/cm2). It can be concluded that adding an appropriate amount of G to the coating can balance the cathodic protection and shielding property of the coating. The equilibrium mechanism was also analyzed in this work.

Shape and size design, preparation and test evaluation of color unit in visible light and infrared camouflage

This study presents a novel method for designing and preparing a visible light-infrared-compatible camouflage sample based on the shape, size of the visible band’s color unit and the infrared band’s material coatings. The coatings were prepared by using the cold spray method on 1 m × 1 m aluminum substrates with a color unit of the regular hexagonal sample (M1) and regular quadrilateral sample (M2). Then the color difference, the temperature difference and image salience value methods were used to analyze the effectiveness of camouflage samples through the real-scene tests. The results indicate that designed and prepared compatible camouflage samples are effective in their surrounding environment. Meanwhile, it can be concluded that M1 has high fusion with a background in visible and infrared bands compared to M2, M1 has 90.6% color similarity and only 0.8% temperature difference, the M2 has 85.4% color similarity and 1.6% temperature difference with the green background. These findings indicate that the cold spray method could compensate for conventional visible light camouflage design limitations. The combination of camouflage color unit design and visible/infrared material coating could be helpful in optical camouflage research. Furthermore, to improve the military equipment’s survival time on the battlefield.

SUBSTANTIATION OF THE CHOICE OF COATING MATERIAL WHEN RESTORING PARTS OF AGRICULTURAL MACHINERY BY COLD GAS-DYNAMIC SPRAYING

Based on the method of cold gas-dynamic spraying, technologies are being created to solve problems of energy and resource saving in various industries and non-traditional and effective methods of production, repair, restoration, anti-corrosion protection, obtaining electrical and heat-conductive, anti-friction and other coatings of functional units, and as well as elements of a wide variety of machinery and equipment. The main feature of cold gas-dynamic spraying is the absence of high temperatures during the formation of metal coatings, therefore, the absence of oxidation of particle and base materials, non-equilibrium crystallization processes, and high internal stresses in the workpieces. Coatings created in this way are a metal matrix with ceramic particles embedded in it. They are characterized by high strength, good performance properties and can be applied in any thickness. One of the important characteristics of coatings is the adhesion strength. Before spraying on any part, it is necessary to find out which coating material will give the best strength characteristics between the two materials. Therefore, before spraying, it is important to study the specifics of the formation of a durable coating for a given part, as well as to compare the strength characteristics of the cold gas-dynamic spraying method with other methods for restoring parts. In this paper, an analysis of various coating materials used in the restoration of parts by the method of cold gas-dynamic spraying is carried out. The strengths and weaknesses of various coating technologies are determined, as well as recommendations for choosing a material when restoring parts by cold gas-dynamic spraying.

Cold-Sprayed Composite Metal-Fluoropolymer Coatings for Alloy Protection against Corrosion and Wear.

Results of studying the properties of composite fluoropolymer-containing coatings formed by the cold spray (CS) method on the surface of constructional steel are presented. Different ways of protective coating formation are proposed. The composition of coatings was studied using SEM/EDX analysis. The incorporation of super-dispersed polytetrafluoroethylene (SPTFE) into the coating increases the corrosion resistance of the copper-zinc-based cold-sprayed coating. Analysis of the electrochemical properties obtained using EIS (electrochemical impedance spectroscopy) and PDP (potentiodynamic polarization) indicates that samples treated with SPTFE on a base copper-zinc coating showed lower corrosion current density and higher impedance modulus (jc = 8.5 × 10-7 A cm-2, |Z|f=0.1 Hz = 5.3 × 104 Ω∙cm2) than the specimen with cold-sprayed SPTFE (jc = 6.1 × 10-6 A cm-2, |Z|f=0.1 Hz = 8.1 × 103 Ω∙cm2). The best anticorrosion properties were revealed for the sample with a cold-sprayed base Cu-Zn layer annealed at 500 °C for 1 h, followed by SPTFE friction treatment and re-annealed at 350 °C for 1 h. The corrosion current density jc of such a coating is 25 times lower than that for the base Cu-Zn coating. The antifriction properties and hydrophobicity of the formed layers are described. Obtained results indicate that cold-sprayed polymer-containing coatings effectively improve the corrosion and wear resistivity of the treated material.

Development of high pressure cold spray coatings of tungsten carbide composites

The current study used a cold spray technique to create WC-Co cermet coatings. In hydroturbine blade applications, deposition of WC-Co cermets using the cold spray technique is difficult. However, the Cold spray method may totally eliminate WC segment degradation as associated to other conservative techniques like laser cladding, plasma spraying and high velocity oxygen fuel (HVOF). In the present work, nitrogen gas was used to spray WC-12Co powder with a cold spray solution. SEM, EDS, and XRD were used to demonstrate microstructure and do phase analysis. The results suggest that applying cold spray has no effect on the WC phase. By applying cold spray to pre-heated WC-12Co powder with low-density particles, it was effectively applied to a solid substrate with higher hardness and lower porosity.