Browse Topic: Graphite
The demand for lightweight, high-efficiency components in electric vehicles (EVs) highlights the critical need for reliable Al-Cu joints with superior electrical and thermal conductivity. While diffusion bonding has emerged as a promising approach, interfacial impurities and voids often degrade joint quality and conductivity. Conventional manual polishing was initially employed to prepare Cu and Al surfaces; however, this method proved insufficient in consistently removing oxides and contaminants, leading to non-uniform bonding. In addition, the larger surface area of the samples made traditional polishing impractical, further motivating the use of electropolishing. To overcome these limitations, we introduce electropolishing pretreatment to achieve cleaner, void-free interfaces. Electropolishing effectively dissolves surface asperities and contaminants, enabling intimate atomic contact during bonding and minimizing the formation of brittle intermetallic phases. A systematic investigation of bonding parameters was conducted using a custom-designed graphite clamping system. Microstructural analyses reveal that advanced polishing plays a pivotal role in producing uniform, impurity-free interfaces, resulting in reduced intermetallic thickness, improved bonding strength, and enhanced current-carrying capability. This study demonstrates the clear advantages of electropolishing over conventional polishing and establishes a scalable pathway to manufacture high-performance conductive joints for next-generation EV motor and power distribution systems.
This research demonstrates a new way to make carbon-based battery materials much safer, longer lasting, and more powerful by fundamentally redesigning how fullerene molecules are connected. Today’s lithium-ion batteries rely mainly on graphite, which limits fastcharging speed and poses safety risks due to lithium plating. These research findings mean progress toward safer electric vehicles, longer-lasting consumer electronics, and more reliable renewable-energy storage.
Researchers at NASA have developed new methods to manufacture carbon materials (e.g., nanotubes, graphene) with holes through the graphitic surface of the particles. The methods generate materials with increased accessible surface area, increased functional groups at damage sites, and improved through-surface molecular transport properties.
The foundation specification (AMS3050) and this category specification (AMS3050/4) cover anti-seize greases conforming to the requirements but using the anti-seize ingredient Molybdenum Disulphide; Graphite only.
A team of inventors from NASA Langley and NASA Ames have created a new type of carbon fiber polymer composite that has a high thermal conductivity. This was achieved by incorporating Pyrolytic Graphite Sheets (PGSs) and Carbon Nanotubes (CNTs), which enhance the material’s ability to transfer heat when compared to typical carbon fiber composites.
Amprius is continually improving its pure silicon anode with nanowire structure that has enabled lithium-ion batteries with energy density and specific energy performance exceeding current state of the art graphite cells by 50-100%, in different cell sizes and form factors. The rooted nanowire structure has very good mechanical stability, electrical conductivity, and connectivity, and allows material expansion within the structure, extending the cycle life to hundreds of cycles. Amprius cells have shown that silicon anode-based batteries can reach 1,300 Wh/L and 500 Wh/Kg while maintaining a cycle life compatible with aerospace, military, and other high-end applications. Moreover, the open nanowire structure enables cells to function at high rates of charge and discharge without overheating, achieving 3000 W/kg power density in cells with over 400 Wh/kg specific energy density. Recent cell design optimizations have substantially improved resilience to thermal runaway conditions, such as internal short circuit and nail penetration, all critical performance parameters for electric flight applications.
One of the most promising applications for the use of hydrogen in vehicles is in the combustion engine. According to the legislation proposal being considered by European Union, hydrogen internal combustion engines (H2ICE) are zero emissions solution. Among the existing solutions, H2ICE is becoming the preferred one on long haul trucks and offroad applications. This is due to the high durability of the powertrain, the lower initial investment when compared to other alternatives, and the possibility of using low purity hydrogen. However, despite the high potential use of hydrogen, because of it is the smallest known chemical element, its use can result in the penetration of hydrogen into metallic materials, with the undesirable effect of embrittlement. This effect occurs mainly when the material surface is exposed to high temperatures and pressures, or under corrosion. By diffusing into the crystal lattice, hydrogen is accumulated in the interstices and crystalline defects, reducing the ductility of the metallic material. Unlike high strength steels, cast irons present graphite that can accommodate diffused hydrogen, delaying the embrittlement effect. The morphology and amount of graphite, as well as the alloying elements and phases present, play a key role in this issue. As shown in a previous work, using a pressurized vessel, cast iron specimens where exposed to an atmosphere of 20% H2 and 80% N2 at 150 bar and 300 °C for 7 days, and hydrogen embrittlement was not verified. In the present work, the effects of hydrogen embrittlement on different cast iron microstructure were evaluated by a qualitative fracture analysis technique. To this purpose, a current density of 16 mA/cm2 was applied for 24 h in electrolytic solution. Hydrogen embrittlement was not verified since the fractures presented in all samples showed river marks, characteristic of brittle fracture, and dimples, characteristic of ductile fracture. This indicates that the hydrogen saturation to generate embrittlement was not reached.
Arsenic and ammonia in ground and surface waters pose significant health risks globally, especially for remote areas where access to safe drinking water is a concern for U.S. military personnel. Current removal materials and methods lack contaminant specificity. This study developed adsorptive resins and membranes specifically targeting arsenate and ammonia removal using molecularly imprinted acrylate polymers supported on graphitic carbon nitride. These materials showed comparable arsenate removal capacity to commercial resins. Higher ammonia removal capacity but lower selectivity was demonstrated by these materials in comparison to commercial resins. This research aims to enhance water treatment materials for ensuring clean drinking water access in remote military locations.
The element niobium (Nb), a transition metal, stands ready to improve the performance of one of the lithium-ion (Li-ion) battery’s confusing array of possible electrode chemistries — the LTO (lithium titanium oxide) anode, which after graphite is the second most-produced. During battery charging, lithium ions leave the positive cathode and move through the battery’s electrolyte to take up positions of higher energy in the anode. During discharge, this process reverses and drives electrons through an external circuit to power the load.
This specification establishes testing methods for testing chemical composition in nickel- and cobalt-based alloys.
Scientists have developed a disposable, paper-based THO sensor consisting of an electrode made of molecularly imprinted graphite. Since MIPs are designed using the target molecule as a template, the team used THO as a template when developing the sensor’s carbon-based electrode paste. The synthesized paste was then loaded onto a printed sensor chip and its THO detection abilities were tested.
Currently, two materials are used as anodes in most commercially available lithium-ion batteries that power items like cellphones, laptops, and electric vehicles. The most common, a graphite anode, is extremely energy dense — a lithium-ion battery with a graphite anode can power a car for hundreds of miles without needing to be recharged; however, recharging a graphite anode too quickly can result in fire and explosions due to a process called lithium metal plating. A safer alternative, the lithium titanate anode, can be recharged rapidly but results in a significant decrease in energy density, which means the battery needs to be recharged more frequently.
Several conventional methods on preparation of exfoliated graphite are in practice. However, their major limitations are poor quality of exfoliated graphite, lower yield, more expensive with higher processing time. To address these issues, a unique method for development of exfoliation of graphite using tri-solvents namely Water, Ethanol and Acetic acid is attempted in the present work. Ethanol acts as a supporting group for the long term stable dispersions of ex-graphite nanosheets. Glacial acetic acid, which readily dissolves in water, penetrates through the layers of graphite sheets and breaks the -C=C bond force between layers with the help of stirring and sonication resulting in exfoliation of graphite layers. Exfoliated graphite nanosheets were produced by using optimized mixtures of water, acetic acid and ethanol. XRD, SEM and FTIR studies have been carried out on the developed exfoliated graphite. Nanosheets of exfoliated graphite with size ranging from 100 nm to 150 nm were obtained while using an optimal mixture of water, ethanol and glacial acetic acid of 75 ml, 40 ml and 200 ml respectively with a stirring time of 6 hrs and sonication time 16 hrs. FTIR studies have confirmed the presence of -C=C at wavenumber of 1652 cm-1 and demonstrates the formation of graphene. It was observed that the quality of exfoliated graphite and yield were improved from the present method of processing of graphene nanosheets. Further, the process time is less when compared with existing conventional methods. As the exfoliated graphite nanosheets possess lower value of coefficient of thermal expansion, excellent chemical resistance & stability coupled with higher flame retardancy, they can be potential candidate novel nano materials for aerospace applications as coatings against the harsh climate of the space.
This study aims to present a numerical structural validation procedure for the drum brake spider component. To implement the procedure, the ANSA, ABAQUS, Fe-Safe, and Minitab engineering software were used for stress analysis, fatigue life calculation, and statistical validation using Weibull distribution. The results obtained from these tools allowed us to determine with acceptable error the spot failure of the component and the number of cycles until the occurrence of the failure. The input data to support the pre-processing of the numerical model and obtain the virtual results were determined from the application and analysis of the following methods: determination of the stress strain curve of the Spheroidal Graphite Iron (SG) material of the component, applied to Theory of Critical Distance (TCD) of fracture mechanics and evaluation of the behavior of Nodular Cast Iron under fatigue life. Given the non-linear characteristics under the conditions of use, the need for correction of numerical elastoplasticity was evaluated. The results of the virtual analysis were compared with experimental data collected in an accelerated durability bench, specific for the component under study, in order to validate the method. The procedure presented in this work proved to be effective, obtaining an error of -0.0039% in the fatigue life estimate compared to the experimentally defined target, and an error of 0.0476% in the maximum main stress estimated in comparison with the experimental stress, allowing the use of this procedure as a form of numerical validation of the component.
Thermoelastic instabilities in the contact of brake friction material cause hotbands and hotspots on the surface of brake disc. These phenomena generate thermal stresses that result in generation of cracks, which limit the lifetime of the discs. In the present work, the influence of the chemical composition of brake discs on the thermoelastic behavior of the system and on the lifetime of the discs was investigated. The experimental evaluation was carried out in an inertial dynamometer using the SAE J3080 standard procedure applied on a brake system. Two discs (namely A and B) with different chemical compositions were subjected to the tests. The brake pad composition was kept fixed. The thermoelastic effects on the inner surface of the disc were observed by contact (thermocouple) and noncontact measurement techniques (thermography), as well as through photographic images of the disc’s surfaces. Disc A showed negligible amount of Nb while disc B exhibited 0.360%. Besides, disc B presented approximately 15% more content of C (Carbon) than disc A. Disc B showed twice the lifespan of disc A. This can be attributed to the smaller thermal gradients observed in disc B, which is in turn related to the higher thermal diffusivity (htd) measured for this rotor. The htd is explained by a greater density of graphite (related to a greater amount of C in the composition), as well as a finer (influenced by Nb) and well-distributed graphite flakes seen in case of disc B.
The efficiency of the traditional machining process becomes limited because of the mechanical properties and complexity of the geometric shape of the processed materials. This difficulty is resolved through the nonconventional machining process. Electric Discharge Machining (EDM) process is one of the popular nonconventional machining processes among all nonconventional machining processes for processing such materials. The main objective of the present research work is to evaluate the effect of percentage weight fraction of reinforcement and process parameters on machining responses during EDM of aluminum (Al) 7075-reinforced boron carbide (B4C) and graphite metal matrix composite (MMC) and optimization of the result. Servo voltage (SVO), pulse-on time (T ON), pulse current (I), and different weight percentages of B4C and graphite reinforcement in aluminum metal matrix composite (AMMC) are selected as a process variable to study the process responses in terms of tool wear rate (TWR) and radial overcut (ROC). The design of the experiment has been performed through the Taguchi analysis and linear regression mathematical model to develop the mathematical relation between process and response parameter. Validation of experimentation work has been done through the Analysis of Variance (ANOVA). Experimentation results show the role of important process parameters that affect mostly TWR and ROC and imply the combined level of input parameters that optimize the process responses.
Foundry industries are very much familiar and rich experience of producing ferrous castings mainly Flake Graphite (FG) and Spheroidal Graphite (SG) cast iron. Grey cast iron material is mainly used for dampening applications and spheroidal graphite cast iron is used in structural applications wherein high strength and moderate ductility is necessary to meet the functional requirements. However, both types of cast iron grades are very much suitable in terms of manufacturing in an economical way. Those grades are commercially available and being consumed in various industries like automotive, agriculture etc, High strength SG Iron grades also being manufactured by modifying the alloying elements with copper, chromium, manganese andcobalt. but it has its own limitation of reduction in elongation when moving from low to high strength SG iron material. To overcome this limitation a new cast iron developed by modifying the chemical composition. Additionally, strengthening mechanism were studied to have a linear relationship of strength and elongation even in higher strength. As an outcome, solid solution ferritic strengthened ductile SG iron developed to meet light weight design requirements. In this paper, the effect of alloying elements, strengthening mechanism, chemical, mechanical, microstructural properties, weight optimization, manufacturing challenges and validation etc, are discussed in detail.
Widespread adoption of renewable energy in the power grid requires the right kind of battery — one that is safe, sustainable, powerful, long-lasting, and made from materials that are plentiful and ethically sourced. Researchers have formulated a new type of cell chemistry for dual-ion batteries (DIB) called graphite||zinc metal aqueous dual-ion battery, which uses a zinc anode and a natural graphite cathode in an aqueous, or water-in-bisalt, electrolyte.
This specification covers molded or extruded bar, rod, and shapes produced from a polyamide-imide (PAI) polymer filled with 12% graphite and 3% polytetrafluoroethylene (PTFE). This is designated as Grade 3 material per AMS3670.
This specification covers molded or extruded bar, rod, and shapes produced from a polyamide-imide (PAI) polymer filled with 20% graphite and 3% polytetrafluoroethylene (PTFE). This is designated as Grade 2 material per AMS3670.
With high peak pressure demands and the need for improved engine efficiency, it has become necessary to use lighter and stronger materials for different engine components. Compacted Graphite Iron (CGI) in this area is a promising candidate and is currently used for many casting parts like cylinder block, head, cylinder liner, exhaust manifold, engine frame, etc. The internal quality of these components made from CG iron is crucial for improved engine performance. The internal quality, in turn, depends upon the soundness and solidification behavior of casting components. However, there exist very limited data on the solidification behavior of CG iron for different engine castings. Due to the narrow range of microstructure stability, CG iron production and its solidification is a quite challenging process. In this paper, a study is undertaken for one such engine component exhaust manifold made from CG iron. An in-depth analysis is carried out on exhaust manifold casting to understand its solidification behavior using a casting simulation software MAGMA. Using the simulation, phenomena associated with fluid flow, temperature distribution, mushy zone formation, hot spot, and shrinkage were examined. Microstructure predictions like nodularity were also studied. Prediction of residual stresses and strains in the casting upon solidification were understood for CG iron through simulation. Finally, a comparison was made with all the above solidification parameters of CG iron with another widely used Si-Mo ductile iron material for the exhaust manifold. CG iron showed improved fluidity, higher heat loss, lesser area of hot spot, and lesser porosity formation tendencies compared to Si-Mo ductile iron. It showed a higher amount of residual stresses than Si-Mo due to differences in thermal conductivity and thermal expansion coefficients. Tendencies for warpage and dimensional stability were also compared and found to be better with CG iron than Si-Mo ductile iron
Graphite plays a crucial role in friction materials, since it has good thermal conductivity, lubricity and act as a friction modifier. The right type, amount, shape, and size of the particles control the performance of the brake-pads. The theme of the study was investigating the influence of size of graphite particles (having all other specifications identical) on performance properties of brake-pads containing graphite particles in the average size of 60 μm, 120 μm, 200 μm and 400 μm. Physical, mechanical and chemical characterization of the developed brake-pads was done. The tribological performance was studied using a full- scale inertia brake dynamometer following a Japanese automobile testing standard (JASO C406). Tribo-performance in terms of fade resistance, friction stability and wear resistance were observed best for smaller graphite particles. It was concluded that smaller size serves best for achieving best performance properties barring compressibility.
The present work aims at investigating the tribological behavior of a newly developed friction materials and its performance is compared with the commercial brake pad under dry sliding conditions. The friction materials were made in the form of cylindrical pin from three different solid lubricants - graphite, molybdenum disulfide (MoS2) and graphene - keeping the other ingredients fixed. The prepared seven samples (BP01- Graphite, BP02- MoS2, BP03- Graphite &MoS2, BP04- Graphene, BP05- Graphene & Graphite, BP06 - Graphene & MoS2, BP07 - Graphene, Graphite & MoS2) were tested in pin and disc machine and compared to investigate the coefficient of friction, wear resistance followed by hardness test and thermal degradation analysis. The results showed that the wear loss and coefficient of friction of the developed friction materials were strongly influenced by the type and percentage of solid lubricants. The performance of the newly developed friction materials is better than the commercial brake pad which signifies that it could be used in commercial automotive applications.
Brake pad is considered to be the most essential part of the vehicle. Owing to environmental requirements, natural materials are the raising alternative sources for manufacturing degradable specimens. The main intern of this work was to study the tribological properties of carbon fibre with Cashew Nut Shell Liquid (CNSL) resin, Cashew Nut Shell (CNS) filler, nano Silicon dioxide (SiO2), alumina and graphite. Four samples of varying composition were prepared under optimum process parametric conditions using compression moulding machine. The prepared samples are taken for tribometer test using pin-on-disc apparatus at room temperature. In this load of 10,20,30,40N and sliding distance of 1000,2000 m are applied and responds like wear rate and co-efficient of friction were noted. In addition, the comparisons of hardness of the specimens before and after the tribometer test were also made to note the behaviour of specimens after exposure to thermal and loaded condition. The sample of 40wt% CNSL resin, 35wt% of Carbon fiber and 10wt% of CNS filler with fixed 10 wt. % of SiO2, 3 wt. % of Al2O3 and 2wt.% graphite shown lesser wear rate and improved coefficient of friction. Hence frictional material of this composition will be a better choice for replacing the conventionally used organic and non-organic brake pad material.
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