Browse Topic: Coating processes

Items (410)
ABSTRACT As metallic parts are used, wear, fracture, galling, warpage, and other forms of obsolescence occur. When these issues progress beyond a predefined level, the parts are either replaced or repaired. Replacement leads to undesirable logistics requirements, especially for those parts requiring difficult-to-source, expensive and/or long-lead-time materials. Repair options are often limited due to strict performance requirements of the parts or concern over the quality of the repair. Two relatively new additive manufacturing (AM) process options exist to complete repairs, including repairs required in theater. Hybrid repair via metal AM followed by precision machining within a single setup offers unique repair options not previously available. Though somewhat limited with respect to the number of alloys currently tested, hybrid AM via directed energy deposition (i.e., powder sprayed into a laser-heated liquid metal pool) offers the possibility to quickly, economically and
Sabo, Kenneth M.Golesich, Brock T.Tims, Michael L.
ABSTRACT Corrosion damage to military ground vehicles costs the U.S. Army around $1.6B per year. A large part of that cost is related to keeping vehicles like the Stryker at their full fighting capability. Corrosion damage has been a common finding on Stryker vehicles and even light corrosion damage, which often reaches 10% of the body thickness or more, can degrade its armor protection rating and require replacement. Recently, cold spray deposition has been shown to be capable of restoring the full ballistic resistance of corrosion damaged high hard steel armor panels. These repairs can be done on-vehicle in depot facilities, using mobile high-pressure cold spray systems. This repair capability can reduce the number of entire side, roof, and floor panels that need to be cut out and re-welded in, which is the only currently approved repair operation for corrosion damage that exceeds allowable depths. Citation: V.K. Champagne, C.A. Widener, A.T. Nardi, G.D. Ferguson, “Structural Repair
Champagne, Victor K.Widener, Christian A.Nardi, Aaron T.Ferguson, Gehn D.
Super Duplex Stainless Steels (SDSS) are attracting attentions of the manufacturing industries due to the excellent corrosion resistance to critical corrosion. But SDSS2507 is the hardest to machine with lowest machinability index among DSS family. Moreover, formation of built-up layer (BUL) and work hardening tendency makes it further difficult to machine. Researchers have the conflict in opinions on using wet machining or dry machining using tool coatings. In this investigation SDSS2507 machining is carried out using uncoated and PVD–TiAlSiN-coated tools. The wet and dry machining environment are compared for increase in cutting speed from 170 m/min to 230 m/min. Excellent properties of PVD–TiAlSiN coatings exhibited microhardness of 39 GPa and adhesion strength of 88 N, which outperformed the uncoated tools. Tool life exhibited by coated tools was four times higher than uncoated tools. Wet machining was found to be ineffective when PVD-coated tools are used, exhibiting the same
Sonawane, Gaurav DinkarBachhav, Radhey
To combat corrosion and wear issues of automotive brake discs, many manufacturers have introduced various surface treatment technologies, such as thermal spraying, laser cladding, and ferritic nitrocarburizing (FNC). Besides those surface treatment technologies, a plasma electrolytic aluminating (PEA) process has also shown to be effective in producing alumina-based ceramic coatings on cast iron substrates, providing an enhanced corrosion resistance. In this study, the PEA-coated brake rotor and FNC-treated brake rotor were comparatively tested in various corrosion conditions, including an electrochemical corrosion test and simulative corrosion experiment, before and after a road driving test. A scanning electron microscope (SEM) and an energy-dispersive X-ray (EDX) were used to observe and analyze morphology and chemical compositions of the surfaces and cross-sections of the tested rotors. The results showed that the new PEA-coated brake rotor demonstrated the best corrosion
Liu, YintingNie, Xueyuan
Graphene has been called “the wonder material of the 21st century.” But graphene has a dirty little secret: it’s dirty. Now, engineers at Columbia University and colleagues at the University of Montreal and the National Institute of Standards and Technology are poised to clean things up with an oxygen-free chemical vapor deposition (OF-CVD) method that can create high-quality graphene samples at scale. Their work, published in Nature, directly demonstrates how trace oxygen affects the growth rate of graphene and identifies the link between oxygen and graphene quality for the first time
The paramount importance of titanium alloy in implant materials stems from its exceptional qualities, yet the optimization of bone integration and mitigation of wear and corrosion necessitate advanced technologies. Consequently, there has been a surge in research efforts focusing on surface modification of biomaterials to meet these challenges. This project is dedicated to enhancing the surface of titanium alloys by employing shot peening and powder coatings of titanium oxide and zinc oxide. Comparative analyses were meticulously conducted on the mechanical and wear properties of both treated and untreated specimens, ensuring uniformity in pressure, distance, and time parameters across all experiments. The outcomes underscore the efficacy of both methods in modifying the surface of the titanium alloy, leading to substantial alterations in surface properties. Notably, the treated alloy exhibited an impressive nearly 12% increase in surface hardness compared to its untreated counterpart
Balasubramanian, K.Bragadeesvaran, S. R.Raja, R.Jannet, Sabitha
University of Wisconsin–Madison engineers have used a spray coating technology to produce a new workhorse material that can withstand the harsh conditions inside a fusion reactor
The wear of the piston ring-cylinder liner system in gasoline engines is inevitable and significantly impacts fuel economy. Utilizing a custom-built linear reciprocating tribometer, this study assesses the wear resistance of newly developed engine cylinder coatings. The custom device offers a cost-effective means for tribological evaluation, optimizing coating process parameters with precise control over critical operational factors such as normal load and sliding frequency. Unlike conventional commercial tribometers, it ensures a more accurate simulation of the engine cylinder system. However, existing research lacks a comprehensive comparative analysis and procedure to establish precision limits for such modified devices. This study evaluates the custom tribometer's repeatability compared to a commercial wear-testing instrument, confirming its potential as a valuable tool for advanced wear testing on engine cylinder samples. The validation tests, achieved through standardized contact
Sediako, Dimitry G.Banerjee, Siddharth
Rotary Bell Atomizers are well established in the automotive industry for top coating applications. This type of atomizer allows to create a uniform coating and is characterized by high productivity. Meanwhile, the effectiveness of the process depends on many complex factors. For instance, the transfer efficiency of the paint material, which is the percentage of the paint reaching the structure surface, ranges from 60-95% depending on the application conditions. Any increase in the transfer efficiency can not only reduce energy and material costs, but also reduce the emission of harmful non-deposited paint particles and the effort to handle them. The use of accurate numerical methods in this process helps to optimize the application process, reduce the number of expensive field experiments, and shortens the development cycle of new vehicles, which ensures predictability of production costs. This paper describes a multidisciplinary framework that allows to simulate the industrial
Panov, DmitriiMenon, MuraleekrishnanZhu, HuaxiangStadik, AlexanderZhang, LingranKotian, AkhileshPeng, ChongMonaco, ErnestoBorra, Ravi KanthBoraey, Mohammed
This study delves into the innovative realm of synthesizing surface alloyed materials by utilizing copper-based metamorphic powders subjected to high-intensity electron beam irradiation. The process involves depositing metamorphic particles onto a stainless-steel substrate, and subsequently exposing the assembly to a powerful electron beam, resulting in the development of distinct surface alloyed layers. A notable advancement was achieved by introducing a second layer of metamorphic powders over the existing alloyed layer, followed by further treatment with the electron beam. The alloyed layers, characterized by a volumetric concentration ranging from 60 to 67%, exhibited a fascinating phenomenon— the formation of abundant borate crystals with the chemical formula Al2.56Fe1.75Ni0.84. This crystal presence significantly elevated the hardness of the surface alloyed layers, showcasing an impressive five to sevenfold increase compared to the substrates. Importantly, the alloyed layers
Dinesh Krishnaa, S.Sangeeth Kumar, M.Dhiyaneswaran, J.Rishi Karthikeyan, V.P.Saran Rithik, B.
This specification covers the requirements for vacuum deposited cadmium
AMS B Finishes Processes and Fluids Committee
Naval Air Systems Command Naval Air Station North Island, CA (619) 545-3415
Simulation tools play a significant role in the automotive industry due to their cost-reducing capabilities in new model development. Computational Fluid Dynamics (CFD) is extensively utilized in various applications, such as vehicle aerodynamics and engine thermal management. However, its application in manufacturing engineering is not yet widespread. One crucial process in automotive manufacturing is the application of the base coat, which provides protection for the final paint layer. This process involves three key steps: bodywork immersion, electrophoretic deposition (E-coat), and bodywork removal from the bath. Each of these steps can be evaluated using appropriate CFD models. During the immersion step, the primary objective is to minimize the presence of trapped air. In the E-coat step, the focus is on controlling the paint layer thickness on the Body-in-white (BIW). Lastly, the drainage analysis aims to minimize the retention of bath fluid, thereby preventing contamination in
Vieira, Tiago Augusto SantiagoAraújo, Pedro HenriqueAbdu, Aline Amaral QuintellaCury, Davi MachadoMonteiro, Henrique Carlos
NASA instrumentation is at risk for contamination from dusty space environments. Additionally, contamination from water and ice buildup can affect instrumentation function. Researchers at the Goddard Space Flight Center have developed a viable dust, water, and ice mitigation optical coating for space flight, aeronautical, and ground applications. The innovation of the LOTUS coating prevents contamination on sensitive surfaces, like optics, that cannot be cleaned during space missions
High-temperature corrosion is a crucial issue in power plant components such as boilers and superheaters when they operate in high-temperature aggressive environments leading to early component failure. As a result, surface modification is critical to protect parts against various types of degradations and increase operational performance at the lowest possible cost. The present study deals with Metco 42C and cenosphere-based composite coating on ASME A387 Grade 22 boiler steel material. The coating compositions were prepared by weight fraction of 5% and 10% cenosphere with Metco 42C and coated on T22 boiler tube material by plasma spray technique. To check the performance a high-temperature cyclic oxidation study at 600°C for 20 cycles in a molten salt environment of sodium sulfate (40%Na2SO4) and vanadium pentoxide (60%V2O5) was carried out and simultaneously corrosion kinetics was evaluated after each cycle. Neutral salt spray (NSS) and cyclic corrosion tests were carried out at
Lakkannavar, Virupakshappa K.Yogesha, K.B.
This specification covers engineering requirements for the grinding of tungsten carbide high velocity oxygen/fuel (HVOF) thermal spray coatings applied to high strength steels (220 ksi and above
AMS B Finishes Processes and Fluids Committee
Engineers, managers, technicians and other automation professionals at most manufacturers understand the value of pretreating metal surfaces of parts to remove corrosion, grease, residue, old coatings, or to roughen the surface of metals prior to coating. By ensuring the items are cleaned down to bare metal, manufacturers can avoid costly warranty issues that result when coatings peel, flake, bubble, or otherwise fail prematurely
Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD) processes deposit material on all surfaces in a process chamber. Over time, the thickness of these deposits increases to the point that material begins to delaminate, producing gas-phase particulates that negatively impact process yield. Remote and in situ chemical etching processes are used to periodically remove these deposits from chamber walls, maintaining chamber cleanliness
Quasicrystalline (QC) coatings were evaluated as leading-edge protection materials for rotor craft blades. The QC coatings were deposited using high velocity oxy-fuel thermal spray and predominantly Al-based compositions. Ice adhesion, interfacial toughness with ice, wettability, topography, and durability were assessed. QC-coated sand-blasted carbon steel exhibited better performance in terms of low surface roughness (Sa ~ 0.2 μm), liquid repellency (water contact angles: θadv ~85°, θrec ~23°), and better substrate adhesion compared to stainless steel substrates. To enhance coating performance, QC-coated sand-blasted carbon steel was further exposed to grinding and polishing, followed by measuring surface roughness, wettability, and ice adhesion strength. This reduced the surface roughness of the QC coating by 75%, resulting in lower ice adhesion strengths similar to previously reported values (~400 kPa). The durability of polished QC coating was evaluated using sand and rain erosion
Yang, QimengDolatabadi, AliGolovin, Kevin
Electroplating is a process whereby an object is coated with one or more relatively thin, tightly adherent layers of one or more metals. It is accomplished by placing the object to be coated on a plating rack or a fixture, or in a basket or in a rotating container in such a manner that a suitable current may flow through it, and then immersing it in a series of solutions and rinses in planned sequence. The advantage to be gained by electroplating may be considerable; broadly speaking, the process is used when it is desired to endow the basis material (selected for cost, material conservation, and physical property reasons) with surface properties it does not possess. It should be noted that although electroplating is the most widely used process for applying metals to a substrate, they may also be applied by spraying, vacuum deposition, cladding, hot dipping, chemical reduction, mechanical plating, etc. The purpose for applying an electroplate and the metals used for various
Metals Technical Committee
The present investigation has been conducted to study the tribological and adhesion properties of X10CrNi18-8 austenitic stainless steel (ASTM 301) coatings deposited on aluminum alloys such as AU4G by using the arc-spraying process. These coatings were made with and without a bond-coat layer, which is constituted by NiAl. The structure of the phases that are present in coatings was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The measurements of microhardness and tribological behavior at different loads were also performed on the surface of the coatings. Adherence test was also carried out using four-point bending tests. The SEM showed that the dense microstructures of coatings have a homogeneous lamellar morphology with the presence of porosities and unmelted particles. The main phase of coating corresponds to a solid solution as a face-centered cubic (fcc). The microhardness of coatings is nearly four times that of the two substrates of aluminum
Sadki, AbdallahYounes, RassimBradai, Mohand AmokraneMesrati, Nadir
This specification covers nonfluorescent magnetic particles in the form of a mixed, ready-to-use suspension in an odorless oil vehicle and packaged in aerosol cans
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Cooling loss reduction is essential to enable further increases in thermal efficiency of reciprocating internal combustion engines. Many in-cylinder cooling loss reduction studies have been carried out by applying various thermal barrier coatings to the piston and/or other in-cylinder surfaces, taking advantage of the lower thermal effusivity of ceramic materials. However, the end result was mostly minimal or in some cases, negative. In our previous study, significant cooling loss reduction was experimentally confirmed by utilizing a mirror-like polished stainless-steel thermal sprayed surface (HVOF: high velocity oxy-fuel) on a forged steel piston. This study firstly investigated an alternative insulating layer material to stainless-steel, along with effects of its thickness on heat transfer by a one-dimensional unsteady numerical model. Results showed that lower thermal effusivity doesn’t always reduce heat transfer, but increases nonuniformity of surface temperature. Next, a
Kawaharazuka, FumihiroUchida, Noboru
The sunrise vision for hydrogen economy lies in efficient, lightweight and durable devices which can convert hydrogen energy into electrical energy. Proton Exchange Membrane fuel cell (PEMFC) is a key hydrogen energy conversion system for transport sector. The efficiency and durability of PEM fuel cell largely depends on cathode electrode and membrane and Bipolar plates (BP Plates) plays an important role in it. BP plates perform the important functions of transporting fuel gases to reactive sites, collecting charges and thus conducting electricity from cell to cell, moisture adjustment of membrane, transport of produced water and provides essential mechanical strength to fuel cell stack. It makes BP plates the backbone of PEM Fuel cell power stack. For BP plates to perform intended functions, it is highly desirable BP plates to possess excellent properties on corrosion resistance, electrical conductivity, thermal conductivity, water wettability, weldability and formability. There is a
Chauhan, ShivPonkshe, Shripadraj
China VI emission standards (Limits and measurement methods for emissions from diesel fueled heavy-duty vehicles, China VI, GB17691-2018) have strict particle number (PN) emission standards and so the coated diesel particulate filter (DPF) technology from the EU and US market has challenge in meeting the regulation. Hence, a coated DPF with higher PN filtration efficiency (FE) is required. Currently, there are two approaches. One is from the DPF substrate standpoint by using small pore size DPF substrate. The other is from the coating side to develop a novel coating technology. Through the second approach, a layer coating process has been developed. The coated DPF has an on-wall catalytic layer from inlet side and an in-wall catalytic coating from outlet side. The DPF has improved PN filtration efficiency and can meet China VI regulation without any pre-treatment. It has lowered soot loading back pressure (SLBP), compared to the DPF with small pore size. The paper will discuss the
Zhao, ChuangWang, LifengLou, DimingRen, Yedi
Cold spray (CS) is a rapidly developing solid-state repair and coating process, wherein metal deposition is produced without significant heating or melting of metal powder. Solid state bonding of powder particles is produced by impact of high-velocity powder particles on a substrate. In CS process, metal powder particles typically of Aluminum or Copper are suspended in light weight carrier gas medium. Here high pressure and high temperature carrier gas is expanded through a converging-diverging nozzle to generate supersonic gas velocity at nozzle exit. The CS process typically uses Helium as the carrier gas due to its low molecular weight, but Helium gas is quite expensive. This warrants a need to explore alternate carrier gases to make the CS repair process more economical. Researchers are exploring another viable option of using pure Nitrogen as a carrier gas due to its significant cost benefits over Helium. However, it shows challenges in achieving desired powder particle velocities
Bhardwaj, DivyanshuBhise, Onkar PSalutagi, Shivayogi SRoberts, Kirstyn
This specification covers a mold release agent in the form of a liquid
AMS P17 Polymer Matrix Composites Committee
This specification establishes requirements for pressure-sensitive adhesive tape designed for masking and color separation during aircraft painting operations
AMS G8 Aerospace Organic Coatings Committee
Laser crystals can be considered the “engines” of solid-state lasers. They are used for gain media, for frequency conversion, and to manage laser characteristics and performance. Like the engine of a car, if laser crystals are clean and working properly, they allow the larger system to operate at a higher level. In the case of a laser system, operating at a high level means creating a stable beam and reaching high optical powers. Some advantages of laser crystals over other solid-state gain media are that they typically offer less absorption, a narrower emission bandwidth, higher transition cross-sections, and higher thermal conductivity. Laser crystals are critical for enabling a wide variety of applications including laser materials processing, laser surgery, sensing, defense applications like rangefinding, and more
This specification covers the material and process requirements for fabricating sandwich radomes having hot-melt, addition-reaction polyimide-resin-impregnated quartz cloth shells and polyimide-resin syntactic foam cores
AMS P17 Polymer Matrix Composites Committee
This specification covers the material and process requirements for fabricating sandwich radomes having polyimide-resin-impregnated quartz cloth shells and polyimide-resin syntactic foam cores
AMS P17 Polymer Matrix Composites Committee
Engineers have created a highly effective way to paint complex 3D-printed objects, such as lightweight frames for aircraft and biomedical stents, that could save manufacturers time and money and provide new opportunities to create “smart skins” for printed parts
Due to the reduced or less-frequent usages of the friction brakes and the lower brake rotor temperature on electrical vehicles (EV), corrosion would much likely occur on brake rotors. Using hard braking to clean the corroded rotor surfaces often leads to extra rotor surface wear. Improvement in corrosion and wear resistance is an important technological topic to brake rotors for EVs. Many original equipment manufacturers (OEM) and their suppliers are exploring surface treatments including laser cladding and thermal spray processes on cast iron rotors to combat the corrosion issues. However, mentioned surface coating processes increase the cost of brake rotors and there is a need to search for cost-effective coating processes. In this research, a new Al2O3-Ni composite coating was proposed for preparation of a commercial cast iron brake rotor using plasma electrolytic aluminating (PEA) followed by electroless nickel plating (ENP) processes. The added nickel was to fit in the intrinsic
Cai, RanSun, JiayiZhang, JingzengTjong, JimiFoots, SeanLavelle, MarkNie, Xueyuan
With the improvement of vehicle comfort requirements of market users, NVH performance has been paid more and more attention. Especially the pure electric passenger vehicle is lack of combustion engine noise masking effect, it is more likely to cause the drivers attention for any abnormal noise. In the steering operation under the low speed acceleration of pure electric vehicles, the cabin interior noise derived from the road and the wind is relatively low, and there is not marketing effect of traditional internal combustion engine noise, any slight abnormal noise is more likely for the drivers and passengers feel unsafe and complain. However, there is lack of systematic analysis and research on the untypical NVH problem in the automotive industry. This paper systematically expounds the test and analysis process of abnormal noise. According to the correlation comparison between the full vehicle and the drivetrain subsystem platform, it is found that the differential assembly is the
Zhang, JunChen, Yu
In recent years, bearing electrical failures have been a significant concern in electric cars, restricting electric engine life. This work aims to introduce a coating approach for preventing electrical erosion on 52100 alloy steel samples, the most common material used on manufacturing bearings. This paper discusses the causes of shaft voltage and bearing currents, and summarizes standard electrical bearing failure mechanisms, such as morphological damages and lubrication failures. Alumina coatings are suitable for insulating the 52100 alloy steel samples because alumina coatings provide excellent insulation, hardness, and corrosion resistance, among other characteristics. The common method to coat an insulated alumina coating on the bearing is thermal spraying, but overspray can cause environmental issues, and the coating procedures are costly and time-consuming. Based on the research, this article briefly discusses employing plasma electrolytic aluminating to coat 52100 alloy steel
Deng, DeweiCai, RanSun, JiayiNie, Xueyuan
The carbon footprint calculation of a catalytic converter coating process at Heraeus Precious Metals is presented in this publication. The emission hot spots are identified and discussed. Heraeus Precious Metals is a German world-wide leading company in the field of precious metal products and Tier-1 Supplier of emission catalytic converter coatings. In the first step of the carbon footprint calculation, all relevant raw materials and production process steps of the coating process are collected and modelled by use of a flowchart. In this case study the manufacturing of the metal honeycomb carrier is not included in the calculation. Transport emissions from the origin of the raw materials to the manufacturing plant of Heraeus Precious Metals in Germany are also considered in the carbon footprint calculation. Included activities for the production of the washcoat dispersion are the mixing of all components by use of an electric agitator and the grinding of the mixture by use of an
Merschak, SimonHehenberger, PeterBonifer, Marcus
This specification covers tungsten carbide-cobalt chrome in the form of powder
AMS F Corrosion and Heat Resistant Alloys Committee
The critical components in earlier were manufactured by mild steel but due to low corrosion resistance, stainless steel and aluminium alloy are being utilised. However a component of aluminium alloy has to be enriched by anodizing for long durability and better corrosion resistance. But peel off, pit formation, low adhesion and white rust formation are still the downfalls faced by the industries in the coated components over cyclic duration. High-Velocity Oxy-Fuel (HVOF) thermal spraying is an adaptable method that can produce high-density coating with less than 1% porosity, high resistant to chemical environment providing better adhesion and increase the life of mating components. Though stainless steel and anodized aluminium alloy offers far superior life span and corrosion resistance but still more expensive than mild steel. This work evaluates the behaviour of HVOF thermal sprayed with tungsten, nickel and chromium containing WC-Cr3C2-Ni coating material over mild steel were found
gopal, ShanthoshR, SoundararajanSakthivel, Vellingiri
In the present work, a system approach to the tribological optimization of passenger car engines is demonstrated. Experimental data and simulation results are presented to demonstrate the role of surface specifications, ring pack, and lubricant on the piston/bore tribology. The importance of in-design “pairing” of low-viscosity motor oils with the ring pack and the cylinder bore characteristics in order to achieve maximum reduction in GHG emissions and improvement in fuel economy without sacrificing the endurance is elucidated. Earlier motored friction data for two different gasoline engines - Ford Duratec and Mercedes Benz M133 - using motor oils of different viscosity grades are now rationalized using AVL EXCITE® piston/bore tribology simulations. The main difference between the engines was the cylinder bore surface: honed cast iron vs thermally sprayed, and the valve train type: direct-acting mechanical bucket (DAMB) vs roller finger follower (RFF). The simulation data show that
Zhmud, BorisTomanik, EduardoJiménez, Antonio J.Profito, FranciscoTormos, Bernardo
This specification covers a cobalt alloy in the form of powder
AMS F Corrosion and Heat Resistant Alloys Committee
Inside an automobile, hundreds of connectors and electrical terminals in various locations experience different corrosive environments. These connectors and electrical terminals need to be corrosion-proof and provide a good electrical contact for a vehicle’s lifetime. Saltwater and sulfuric acid are some of the main corrosion concerns for these electrical terminals. Currently, various thin metallic layers such as gold (Au), silver (Ag), or tin (Sn) are plated with a nickel (Ni) layer on copper alloy (Cu) terminals to ensure reliable electrical conduction during service. Graphene due to its excellent chemical stability can serve as a corrosion protective layer and prevent electrochemical oxidation of metallic terminals. In this work, effects of thin graphene layers grown by plasma-enhanced chemical vapor deposition (PECVD) on Au and Ag terminals and thin-film devices were investigated. Various mechanical, thermal/humidity, and electrical tests were performed. In addition, a systematic
Zhang, Suki NaifangChen, ZhihongArfaei, Babak
This study investigates simultaneous improvement in thermal efficiency and cooling loss in the wider operating condition. To suppress the heat flux of the piston, the piston top and cavity were treated with thin thermal spraying of stainless steel. Thermal diffusivity of stainless steel (X5CrNiMo17-12-2, SUS316) is very low in comparison with the forged steel piston raw material (34CrMoS4, SCM435) to sustain local surface temperature at where spray flame directly interfered. In addition, its surface roughness was very fine finished aiming to reduce the convective heat transfer. The experimental results with the stainless-steel coated piston by utilizing a single cylinder engine showed the significant improvement in both cooling loss and thermal efficiency even in higher load operating conditions with compression ratio of 23.5:1. From the analysis of the experimental result, it is assumed that not only convective heat transfer but radiative heat transfer could play an important role in
Kawaharazuka, FumihiroUchida, NoboruOsada, Hideaki
Nissan’s variable compression turbo (VC-Turbo) engine has a multilink mechanism that continuously adjusts the top and bottom dead centers of the piston to change the compression ratio and achieve both fuel economy and high power performance. Increasing the exhaust gas recirculation (EGR) rate is an effective way to further reduce the fuel consumption, although this increases the exhaust gas condensation in the cylinder bores, causing a more corrosive environment. When the EGR rate is increased in a VC-Turbo engine, the combined effect of piston sliding and exhaust gas condensation at the top dead center accelerates the corrosive wear of the thermal spray coating. Stainless steel coating is used to improve the corrosion resistance, but the adhesion strength between the coating and the cylinder bores is reduced. Trial production of the coatings with different linear expansion coefficients was conducted, and the sensitivity of the linear expansion coefficient and adhesion strength was
Hirayama, HayatoHiguchi, TsuyoshiHoshikawa, HiroakiNoshi, YoshitsuguTerada, DaisukeOosaki, Mototsugu
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