Improve Heat Resistance of Composite Engine Cowlings Using Ceramic Coating Materials, Experimental Design and Testing
Abstract Oven and flame tests were designed and conducted to evaluate the heat resistance of a ceramic coating material, Cerakote C-7700Q, and evaluate its viability to replace the intumescent coating as one painting material for helicopter engine cowlings. The test results showed that the currently used painting scheme of the engine cowlings failed the 220°C oven test while after replacing the epoxy seal coat with the Cerakote, the new painting system passed the 220°C test in regards to painting bubbling. This study explained why serious appearance defects occurred in the inner skin of the engine cowling when the aircraft is hovering and suggested that one most time- and cost-effective solution is to repaint the current engine cowlings with a new three coating system of Cerakote, surface protection HS7072-622, and intumescent paint as a fireproof lacquer.
Rig Test of Diesel Combustion Chamber with Piston Coated by Optically Simulated Semitransparent PSZ-Ceramic
Abstract Running efficiency of LHR diesel has been confirmed by mean of well-known types of heat-insulating (HICs) or thermal barrier (TBCs) coatings. These materials are considered as a semitransparent media SHICs (STBCs) in the form of an ensemble of diffraction objects, forming own thermoradiative fields under the scattering theory laws. This problem is relevant for a diesel with combustion chamber (CC) in which intensive IR radiation reaches ~50% of total thermal flux. The authors indicate that predetermined selection of optical and thermoradiative parameters in the same spectrum for coatings (due to specific structural composition and porosity) can change their temperature fields inside its subsurface zone and hence in the CC gas volume. Previous author's research of optical parameters for ceramic semitransparent materials allowed offering SHIC (STBC) samples for rig testings.
Abstract For the purpose of improving vehicle fuel efficiency, it is necessary to reduce energy loss in the alternator. We have lowered the resistance of the rectifying device and connecting components, and control the rectifying device with an IC to reduce rectification loss. For the package design, we have changed the structure of the part on which the rectifying device is mounted into a high heat dissipation type. The new structure has enabled optimizing the size of the rectifying device, resulting in the reduction of size of the package. In addition, the rectifying device is mounted using a new soldering material and a new process, which has improved the reliability of the connection. Moreover, since the alternator has introduced a new system, the controller IC has a function for preventing malfunction of the rectifying device and a function for detecting abnormalities, in order to ensure safety.
Advanced Ceramic Substrate with Ordered and Designed Micro-Structure for Applications in Automotive Catalysis
Abstract This study describes an innovative monolith structure designed for applications in automotive catalysis using an advanced manufacturing approach developed at Imperial College London. The production process combines extrusion with phase inversion of a ceramic-polymer-solvent mixture in order to design highly ordered substrate micro-structures that offer improvements in performance, including reduced PGM loading, reduced catalyst ageing and reduced backpressure. This study compares the performance of the novel substrate for CO oxidation against commercially available 400 cpsi and 900 cpsi catalysts using gas concentrations and a flow rate equivalent to those experienced by a full catalyst brick when attached to a vehicle. Due to the novel micro-structure, no washcoat was required for the initial testing and 13 g/ft3 of Pd was deposited directly throughout the substrate structure in the absence of a washcoat.
Abstract Starting in the late '90s, a new and innovative brake disk technology entered the high performance passenger car market. Approx. 2 years later, small volume production of carbon-ceramic brake disks started. In the past ten years the number of cars equipped with the new generation of ceramic matrix composite (CMC) brake disks has continuously increased, with main usage in low volume, high horse power applications. The goal of this paper is to give an overview of the system specific boundary conditions as well as today's and tomorrow's targets and aspects of friction material development used in CMC-disk based brake systems. Starting with a description of the system component properties, a comparison of typical CMC vs. standard gray cast iron disk (GCI) applications will be made. The impact of the component properties, especially the disk as friction counterpart to the pad, will be shown by comparing industry standard test scenarios.
Development of Aluminum Powder Metal Composite Material Suitable for Extrusion Process used for Cylinder Sleeves of Internal Combustion Engines
Abstract There are a couple of ways to manufacture aluminum cylinder blocks that have a good balance between productivity and abrasion resistance. One of them is the insert-molding of a sleeve made of PMC (Powder Metal Composite) by the HPDC (High Pressure Die Casting) method. However, in this method, cracks are apt to occur on the surface when the PMC sleeve is extruded and that has been a restriction factor against higher extrusion speed. The authors attempted to raise this extrusion temperature by eliminating the Cu additive process from the aluminum alloy powder in order to raise its melting point by approximately 50 °C. This enabled the wall of the extruded sleeve to be thinner and the extrusion speed to be higher compared to those of a conventional production method while avoiding the occurrence of surface cracks.
Zirconium dioxide (ZrO2) doped with Yttria exhibits superplastic behaviour, corrosion resistance and excellent ion conducting properties  at moderate temperatures and thus it can be used as an electroceramic to measure the pH of high temperature water used in fuel cells. Several fabrication processes are available for preparation of zirconia ceramics. This research focused on the study of using Spark Plasma Sintering (SPS) process to prepare Yttria Stabilized Zirconia (YSZ) ceramic. 8 mol% YSZ was subjected to varying SPS sintering conditions. Samples were sintered by changing the heating cycle, dwell time, sintering pressure and cooling cycle. Subsequently, these parameters were related to the densification characteristics of the as-sintered YSZ. The results of specific gravity measurements and microstructure evaluation suggest that stepped heating followed by a slow cooling results in YSZ with highest relative density (99.9%).
Abstract With the ever increasing emphasis on vehicle occupant safety, the safety of pedestrians is getting obscured behind the A-pillars that are expanding in order to meet the federal roof crush standards. The serious issue of pillar blind spots poses threats to the pedestrians who easily disappear from driver's field of view. To recognize this blinding danger and design the car around the driver's eye, this paper proposes the implementation of Aluminum Oxynitride marked under name AlON by Surmet Corporation for fabrication of A-pillars that can allow more than 80% visibility through them. AlON is a polycrystalline ceramic with cubic spinel crystal structure and is composed of aluminum, oxygen and nitrogen. With hardness more than 85% than sapphire, its applications range from aerospace to defense purposes which qualify it in terms of strength and thus imply that it can be conveniently used as A-pillars in vehicles.
Abstract Honing is a low-speed abrading process to remove metallic and non-metallic materials from a surface. Honing corrects surface errors produced by other machining operations prior to honing. Moreover,, the honing grooves, the volume and the direction of the valleys control the amount of oil available, by keeping the oil on the bore surface and by improving the spreading of the oil. The traditional honing process that uses ceramic abrasives has been replaced by the superior abrasives that is Metal Bonded Diamond [1,2]. However, the main drawback of diamond honing is that it leaves more torn metal and folded metal on surface . The folded and / or torn metal partially covers the honing grooves and interrupts oil flow in groove. Hence, it causes abrasive wear as axial scratches on the cylinder surface. Diamond is the strongest material known that is less friable, wear very little, requires more pressure and tends to plough through metal surface rather than cut.
Theoretical and Experimental Analysis of Ash Accumulation and Mobility in Ceramic Exhaust Particulate Filters and Potential for Improved Ash Management
Ash accumulation in the channels of ceramic, honeycomb-type particulate filters is controlled by several key parameters, which are the focus of this study. Ultimately, it is the formation of ash deposits, their transport, and the manner in which the ash accumulates in the particulate filter, which determines the useful service life of the filter and its resulting impact on engine performance. Although significant variations in ash deposit properties and their spatial distribution within the filter channels have been reported, depending on the filter's application, understanding the key parameters and mechanisms, such as the effects of exhaust flow and temperature conditions, as well as the processes occurring during filter regeneration events (whether passive or active) are critical in developing improved filter ash management strategies.
Experimental Investigation on Three Different Ceramic Substrate Materials for a Diesel Particulate Filter
Three different ceramic substrate materials (Silicon Carbide, Cordierite and Aluminum Titanate) for a Diesel Particulate Filter (DPF) for a European passenger car diesel engine have been experimentally investigated in this work. The filters were soot loaded under real world operating conditions on the road and then regenerated in two different ways that simulate the urban driving conditions, which are the most severe for DPF regeneration, since the low exhaust flow has a limited capability to absorb the heat generated by the soot combustion. The tests showed higher temperature peaks, at the same soot loading, for Cordierite and Aluminum Titanate compared to the Silicon Carbide, thus leading to a lower soot mass limit, which in turn required for these components a higher regeneration frequency with draw backs in terms of fuel consumption and lube oil dilution.
Previous research has highlighted that the formation of a sustained friction film, desired for stable and predictable friction performance, is highly dependent upon the region of the substrate (CMC) being examined. In attempt to improve the friction performance, notably bedding-in, research at LU has been developing coatings aimed at ensuring friction film development across the substrate. This paper focuses on the performance of one of these coating formulations, and examines the performance of this on a laboratory scale dynamometer. Subsequently, the coating has then been applied to a full size brake disc, as used on a prestige vehicle, for dynamometer testing at an industry scale for comparative purposes. On both lab and full scale samples the bedding performance shows improvements over the standard material, and at the full scale the coating indicates improved stability of subsequent friction performance through a modified AK Master test schedule.
This manuscript describes two different design configurations for a novel environmentally-friendly automotive oil filter. In both cases the filter seamlessly retrofits existing engine applications. The filter element is housed in an easy-to-dismantle casing. The filter element may be replaced at every oil change, but not the casing which may last the lifetime of the engine. The filter element is made of ceramic honeycomb material, which typically possesses high-filtration efficiency characteristics and large contaminant accumulation capacity. When a filter element is replaced with a new unit, the old unit is sent out for treatment so that it can be reused. These cartridges are practical, durable, cost effective, user-friendly and environment-friendly.
High temperature power electronics have become a vital aspect of future designs of compact power converters for applications including power conditioning and distributed motor/actuator controls. However, the development of high temperature capacitors had lagged far behind other system components (e.g. semiconductor switches and that can operate at temperature >200°C). The performance of these systems would benefit significantly from components and packaging designed and optimized for high temperature (200°C to 400°C) under generally harsh environmental conditions. In this paper it will be demonstrated that high temperature materials can be successfully fabricated into multilayer ceramic capacitors (MLCC). The properties of various capacitors having application range 200∼500°C will be presented.
The capability of theoretical durability studies to offer an efficient alternative methodology for predicting the potential performance of catalysts has improved in recent years. In this regard, multi-scale theoretical methods for predicting sintering behavior of Pt on various catalyst supports are being developed. Various types of Pt diffusions depending on support were confirmed by the micro-scale ultra accelerated quantum chemical molecular dynamics (UA-QCMD) method. Moreover, macro-scale sintering behavior of Pt/ɣ-Al2O3, Pt/ZrO2 and Pt/CeO2 catalyst were studied using a developed 3D sintering simulator. Experimental results were well reproduced. While Pt on ɣ-Al2O3 sintered significantly, Pt on ZrO2 sintered slightly and Pt on CeO2 demonstrated the highest stability against sintering.
Tribological Aspects of Carbon Ceramic and Cast-Iron Brake Rotors with Organic Pad Materials in Simulation and Measurement
Over the last two decades, intensive research in the field of innovative brake rotor materials for high performance vehicles has been done. Due to the market demand for lightweight components with high strength even at elevated temperatures, most new concepts are based on fiber-reinforced materials . The most prominent concept is a silicon carbide matrix material with embedded carbon fibers (C/C-SiC), which penetrated into the market for brake rotors in 2000 [2,3]. Such carbon ceramic brake rotor systems (CKB) have already been made available for a wide range of premium sedans, SUVs and sports cars. In terms of tribology, these rotors pose new challenges for an understanding of the relevant friction phenomena in the boundary layer, as well as for suitable formulations of brake pad materials. The brake system's macroscopic tribological performance with such pads is determined by a closed-loop interaction between heat, wear and sliding resistance on the micro scale.
High-temperature, high-power capacitors are integral components being developed for high-temperature electronics to be used in aerospace, automotive, and other applications. Presently, a wide range of materials and capacitor technologies are being actively developed to address the needs of high temperature applications. Literature and experimental survey of existing materials and technologies focusing on commercially viable technologies has been made. Key parameters for characterizing and assessing capacitors have been compiled. Of the key competing capacitor technologies, including electrolytic, ceramic, polymer thin-film, and supercapacitors, none were found to be clearly superior to the others, thus requiring trade-offs between available choices. The review of these capacitors will be presented with respect to specific energy density, temperature capability, cost, ripple current capability, and failure tolerance.
The role of the ceramic abrasives including zircon (ZrSiO4), alumina (Al2O3), and silicon carbide (SiC) in non-asbestos organic (NAO) brake friction composites were summarized through preparation of friction composites, friction performance tests, and friction surface analysis. The characteristic of the abrasives is higher hardness compared with the cast iron disc. The brake friction composites without abrasives show the lower friction coefficient (μ) and lower specific wear rate due to the adhesion friction effect. Adding the abrasives to friction composites, the values of μ can be enhanced and the wear rate was higher due to the abrasion friction effect. According to friction surface characterized by SEM with EDX, the friction layers were observed and analyzed.
This paper investigates the application of thick film hybrid circuit technology on ceramic substrate in comparison to the main stream substrate FR-4 (Flame Retardant 4) for PCB implementation. The study is based on computer models for these very substrates in order to simulate the propagation of heat through convection and conduction within the material boundaries. In order to simulate electronic components surface mounted, different heat sources are randomly arranged on physical contact to the surface of the material under investigation. The results emphasize and discern the usage of both substrates and its most suitable environment verifying the application towards vehicular integration. Future study may include experimental analysis for simulated data verification and validation of thick film hybrid circuit technology for the automotive industry.
Reduction of Nano-Particle Emissions from Gasoline 2-stroke Engines Using CLM™ Ceramic Exhaust Filters
GEO2 Technologies has developed an extruded fiber-based cross linked microstructure (CLM™) for use as a nano-particulate filter in gasoline 2-stroke exhaust emission control. CLM™ materials exhibit high porosity, narrow pore-size distribution, robust thermo-mechanical properties, and are extruded into high cell density honeycomb structures for wall-flow filter applications. GEO2 has demonstrated basic emission performance and durability of the CLM™ filter on a Piaggio 50cc scooter as well as on a 29cc Homelite leaf blower. The results show significant reduction in particulate emissions of greater than 97% while maintaining gas phase emissions (leaf blower) and without significant impact on engine performance or power output. In addition, a 16,000 km dynamometer durability test was conducted on the Piaggio scooter. During testing, ash loading in the CLM™ filter exceeded 10 grams/liter.
A catalyzed ceramic filter has been used on diesel engines for diesel particulate matter emission control. A key design criteria for a diesel particulate filter is to maximize DPF performance, i.e. low back pressure and compact size as well as near continuous regeneration operation. Based upon the modeling and deep understanding of material properties, a DPF system design has been successfully applied on a high performance diesel engine exhaust system, such as the Audi R10 TDI, the first diesel racing car that won the most prestigious endurance race in the world: the 24 hours of Le Mans in both 2006 and 2007. The design concept can be used for other materials and applications
Stringent emission regulations call for advanced catalyst substrates with thinner walls and higher cell density. However, substrates with higher cell density increase backpressure, thinner cell wall substrates have lower mechanical characteristics. Therefore we will focus on cell configurations that will show a positive effect on backpressure and emission performance. We found that hexagonal cells have a greater effect on emission and backpressure performance versus square or round cell configurations. This paper will describe in detail the advantage of hexagonal cell configuration versus round or square configurations with respect to the following features: 1 High Oxygen Storage Capacity (OSC) performance due to uniformity of the catalyst coating layer 2 Low backpressure due to the large hydraulic diameter of the catalyst cell 3 Quick light off characteristics due to efficient heat transfer and low thermal mass
The effect of web thickness on emission performance, pressure drop, and mechanical properties was investigated for a series of catalyzed ceramic monolith substrates having cell densities of 900, 600 and 400 cpsi. As expected, thinner webs provide better catalyst light off performance and lower pressure drop, but mechanical strength generally decreases as web thickness is reduced. Good correlations were found between emission performance and geometric parameters based on bare and coated parts. An improved method for estimating the effects of cell density and web thickness on bare substrate strength is described, and the effect of porosity on material strength is also examined. New mechanical strength correlations for ceramic honeycombs are presented. The availability of a range of ceramic product geometries provides options for gasoline exhaust emission design and optimization, especially where increased levels of performance are desired.
A Cummins ISB 5.9 liter medium-duty engine with cooled EGR has been used to study an early extrusion of an advanced ceramic uncatalyzed diesel particulate filter (DPF). Data for the advanced ceramic material (ACM) and an uncatalyzed cordierite filter of similar dimensions are presented. Pressure drop data as a function of mass loadings (0, 4, and 6 grams of particulate matter (PM) per liter of filter volume) for various flow rate/temperature combinations (0.115 - 0.187 kg/sec and 240 - 375 °C) based upon loads of 15, 25, 40 and 60% of full engine load (684 N-m) at 2300 rpm are presented. The data obtained from these experiments were used to calibrate the MTU 1-D 2-Layer computer model developed previously at MTU. Clean wall permeability determined from the model calibration for the ACM was 5.0e-13 m2 as compared to 3.0e-13 m2 for cordierite.
Stricter emission regulations on Heavy-Duty Diesel (HDD) engines have brought more demanding conditions to the engine piston ring pack. This work shows and discusses some of the new features of modern HDD ring packs. The presented ring pack comprises a fully nitrided, PVD (Physical Vapor Deposition) coated, top ring. The second ring can still be a cast iron, Chromed Plated but there are also nitrided steel projects for higher durability and robustness. The oil control ring is a narrow, for better conformability, I-Shaped nitrided. Some of the ring characteristics are discussed in the paper: the PVD coating showed excellent compatibility with the smoother cylinder finishes that are being used to reduce Lube Oil Consumption. PVD coated top rings also presented lower radial wear when compared with the traditional Ceramic-Chromium coating.
Magnetostrictive and piezoceramic materials combine specific energy with speed, enabling fast and powerful but compact transducers. These materials, used in US Navy sonar for decades, elastically strain under the influence of a magnetic or electric field. Piezoceramics become active when electrically poled. Poling being artificial, the ceramic loses its piezoelectric properties under overstress, overstrain, overvoltage, or overheating, conditions present in a diesel engine that limit injector performance. In contrast, a magnetostrictive alloy of terbium, dysprosium, and iron will not permanently degrade under the same conditions, enabling an injector to be pushed to the highest possible speed. Quantum mechanics dictate that the non-bonding 4f electron cloud of the terbium atom be oblate, not spherical, an inherent property that connects magnetic and elastic influences.
Ceramic Foams as Catalyst Substrates: Pre-catalyst Application Homogenising the Exhaust Flow upstream of Aftertreatment Devices
Non-homogeneities in the exhaust line regarding flow distribution and mixing of exhaust gases upstream of catalytic converters or particulate filters are a major source of conversion efficiency reduction due to partial volume utilization. Current supports for catalytic converters use a honeycomb monolithic substrate with only a limited potential for increased wall contacts of the gas molecules due to their laminar channel flow profile. Non homogeneities of the flow distribution at the entering cross section of the catalytic converter prevail also inside the converter channels since no momentum exchange is possible perpendicular to the main flow direction. The ceramic based foams developed and patented by Empa are a promising alternative. In the upstream of exhaust aftertreatment devices they ceramic foams redistribute the exhaust gases homogenizing the flow, enhancing turbulence and species mixing, without increasing flow resistance to prohibitive levels.
Advanced Loop Heat Pipe Evaporator with Ceramic Nanostructured Composite of Alumina, Alumina-Silica Oxide as a Wick Structure
Nowadays LHP (CPL) is widely used in thermal control systems for space and ground applications. Wick structure is a key element which plays at least two roles: capillary pump to move a working fluid from condenser to the heat loaded zone and thermal and hydraulic breaker between liquid and vapor in LHP (CPL). This paper is devoted to the R&D of LHP with advanced low-cost ceramic wick structure, which has a high capillary pressure head and low thermal conductivity. First set of tests with acetone as a working fluid was done in Porous Media Laboratory, Minsk, Belarus to prove the possibility to use such kind of wick in present and future designs of LHP (CPL).
Concurrent CO2 Control and O2 Generation for Space Suits and Other Advanced Life Support: A Feasibility Study
The partial electrochemical reduction of carbon dioxide (CO2) using ceramic oxygen generators (COGs) is well known and widely studied. Conventional COGs use yttria-stabilized zirconia (YSZ) electrolytes and operate at temperatures greater than 700 °C. Operating at a lower temperature has the advantage of reducing the mass of the ancillary components such as insulation and heat exchangers (to reduce the COG oxygen output temperature for comfortable inhalation). Moreover, complete reduction of metabolically produced CO2 (into carbon and oxygen) has the potential of reducing oxygen storage weight if the oxygen can be recovered. Recently, the University of Florida developed novel ceramic oxygen generators employing a bilayer electrolyte of gadolinia-doped ceria and erbia-stabilized bismuth oxide (ESB) for NASA's future exploration of Mars.
A novel processing method for fabricating high porosity microcellular ceramic foams for sound absorption applications has been developed. The strategy for fabricating the ceramic foams involves: (i) forming some shapes using a mixture of preceramic polymer and expandable microspheres by a conventional ceramic forming method, (ii) foaming the compact by heating, (iii) cross-linking the foamed body, and (iv) transforming the foamed body into ceramic foams by pyrolysis. By controlling the microsphere content and that of the base elastomer, it was possible to adjust the porosity with a very high open-cell content (ranging between 43 - 95%), high microcellular cell densities (9 × 108 - 1.6 × 109 cells/cm3) and desired expansion ratios (3 - 6 folds). Sound absorption testing has been performed using ASTM C-384 standard test. The preliminary results show that ceramic foams are candidate sound absorption materials.