Iron Disc Research Articles

Wear-emission correlation in brake materials

This study is based on a test campaign of 10 brake couples on a reduced-scale dynamometer, with the aim of exploring the relationship between wear and fine airborne particle emissions from brake materials. Different Non-Asbestos Organic (NAO) and low-metallic friction materials sliding against grey cast iron discs, also against High-Velocity Oxygen Fluid (HVOF) coating, were investigated. The tribological tests reproduce mild sliding conditions through brake cycles designed using a factorial approach, with contact pressure levels of 1–3.5 MPa and sliding velocities ranging from 4 to 16 m/s.The wear rate is quantified using the specific wear coefficient, Ka, and the emissions were quantified with the concept of Emission Factors (EF). NAO materials exhibit an EF of approximately 1.5–2.2 mg/km/corner when coupled with cast iron discs. Conversely, low-metallic materials show EF in this range only when sliding against the hard-coated disc. When coupled with cast iron discs, the EF of low-metallic materials ranges from 5.7 to 11.1 mg/km/corner. A strong correlation between the system Ka and EF values is found and this is leveraged to derive considerations on the permissible Ka to adhere to emission limitations in the context of the EU7 regulation.

Enhanced tribological performance of MoS2 and hBN-based composite friction materials: Design of tribo-pair for automotive brake pad-disc systems

This research comprehensively analyzes the friction and wear behavior of composite friction materials when dry sliding against grey cast iron and laser-clad nickel-based (LC1) and iron-based (LC2) alloy discs. The composite friction materials (P1, P2, P3, P4, P5, and P6) under investigation contain graphite, MoS2, and hBN-based solid lubricant synthesized through the powder metallurgy technique. Tribological tests were conducted using a pin-on-disc configuration to simulate the dynamic interaction between the composite materials and the laser-clad grey cast iron discs. The tests were performed at a 60 N load, 6283.19 m sliding distance, and 2.094 m/s sliding velocity under dry sliding conditions. The results provide valuable insights into the effectiveness of MoS2 and hBN-based solid lubricant composites in reducing friction and wear when in contact with iron and nickel alloy-based laser-clad grey cast iron surfaces. The study elucidates the mechanisms governing tribological behavior, including the formation of friction plateaus and the role of laser-clad counter-discs in reducing wear. The specific wear rate of the nickel-based laser-clad counter disc (LC1) and iron-based laser-clad (LC2) system improved by 63.76 % and 48.32 %, respectively, compared to the conventional grey cast iron disc system when using the hBN-based pin (P6). Additionally, the specific wear rate of the hBN-based pin was 38.49 % lower than the conventional graphite-based pin when sliding against the grey cast iron counter-disc. Artificial Neural Network (ANN) was used to validate the wear rate of the best-performing tribological pair, namely the hBN-based pin (P6) and LC2 counter discs, through supervised learning.

Design and Control of the Natural Frequency of Brake Discs in the Aspect of the Gray Cast Iron Production Process.

The results of research on the influence of the chemical composition of cast iron and its potential changes in the production cycle on the elastic properties and the correctness of numerical simulations of the natural frequency of ventilated brake discs are presented. The tests were carried out for three grades of gray cast iron with flake graphite with a eutectic saturation coefficient ranging from 0.88 to 1.01. A quantitative metallographic assessment of the pearlitic cast iron matrix and graphite precipitates was carried out, and the hardness and compressive/tensile strength of individual cast iron grades were determined, taking into account the limit contents of the alloying elements. Next, ultrasonic tests were performed, and the elastic properties of cast iron were determined. Based on the obtained data, a numerical modal analysis of brake discs was performed, the results of which were compared with the actual values of an FRF frequency analysis. The error of the computer simulations was estimated at approx. 1%, and it was found that the accuracy of the calculations of the first natural frequency did not depend on the dimensions (size) of the discs and the chemical composition of the cast iron from which they were cast. The functional relationships between the chemical composition of cast iron, its strength and elasticity and the first natural frequency of the disc vibrations were determined, and a database of the material parameters of the produced cast iron grades was developed. An implementation example showed the validation of the brake disc design with natural frequency prediction and demonstrated a high convergence of the experimental results with the simulated values. Using I-MR control cards, both the effectiveness of designing and predicting the natural vibrations of brake discs based on the implemented material database as well as the stability of the gray cast iron production and disc casting processes were confirmed.

Properties of Laser-Alloyed Stainless Steel Coatings on the Surface of Gray Cast Iron Discs

The influence of laser-alloyed stainless steel coatings on the properties of the surfaces of cast iron discs, such as friction-induced vibration and noise, friction coefficient, residual stress, hardness, and corrosion resistance, was investigated in this study. The experimental results show that after laser alloying, the surface hardness of the cast iron discs increased significantly. The residual stresses on the surfaces of the laser-alloyed discs changed from tensile to compressive residual stresses, while any compressive residual stresses increased by more than six times. Most of the laser-alloyed discs demonstrated better performance in friction-induced vibration and noise damping and friction reduction. Metallographic observation and XRD (X-ray diffraction) analysis results show that the laser-alloyed layer is mainly a mixture of acicular martensite and dendritic material, while the phase composition of laser-treated discs is mainly martensitic, [Fe, Ni], Fe3Si, Cr23C6, and austenite, which plays a significant role in the improvement of the properties of the laser-alloyed cast iron in physics, tribology and corrosion resistance. This research has significance for the laser surface treatment of various cast irons and steels, which is an increasingly important manufacturing technology in the vehicle friction brake industry.

The effect of solid lubricants in the brake friction composite on brake emissions: A case study with graphite, Sb2S3, and MoS2

Particulate matter produced during brake application was investigated, focusing on the effect of the solid lubricants in the brake friction composite, such as graphite, antimony trisulfide, and molybdenum disulfide. Results showed that the brake emission was significantly affected by the solid lubricant type and braking temperatures. Antimony trisulfide caused high brake emissions at moderate temperatures, whereas graphite produced high emissions at elevated temperatures. The brake emission at moderate temperatures was affected by the aggressiveness of the composites and the presence of friction films on the gray iron disc surface. In contrast, the brake emissions at elevated temperatures were determined by the thermal decomposition of the composite and the oxidation of solid lubricants.

Microstructure and Wear Resistance of Fe3Al Coating on Grey Cast Iron Prepared via Direct Energy Deposition

In this study, the potential of Fe3Al coating material as an environmentally friendly alternative to coatings containing critical elements for brake discs was investigated. A buffer layer of Cr–Mo steel (Ferro 55) that was about 500 µm thick was applied on a gray cast iron disc to enhance the coating quality and prevent the formation of hot cracks during solidification. The microstructural analysis of the cross-section of the coating showed that the buffer layer diffused into the Fe3Al coating, forming a combination of Fe3Al, Fe, and Fe3AlC0.5 phases. The tribological properties of the Fe3Al-coated disc were evaluated using pin-on-disc tests against two different copper-free friction materials extracted from commercial brake pads. The wear results show a coefficient of friction comparable to that of an uncoated disc (≈0.55), but with a reduction in particulate matter (PM) emissions, which decreased from 600 to 476 #/cm3. The last issue is an interesting aspect that is gaining increasing importance in view of the upcoming international standards.

Fluorescent‐Dye‐Doped Nanoporous Silica Powder for Imaging of Latent Fingerprints (Levels 1–3) and Case Studies

AbstractNovel naphthalimide based fluorescent dye NI‐1 possess (i) high quantum yield, (ii) blue emission (λem=450 nm), (iii) CIE coordinate (x=0.21, y=0.35) with 39 % blue colour purity in solid state, (iv) photochemical and thermal stability up to 200 oC and (v) low cytotoxicity to normal cells L929. NI‐1 was doped in nano porous silica and used as fluorescent powder for imaging of latent fingerprints (LFPs) on coloured surfaces, barcode, wood, brick, leaf and engraved steel beside other common household porous and nonporous surfaces. We demonstrated visibility of levels 1–3 on ceramic tile, glass, paper, steel, iron and compact disc using NI‐1 doped fluorescent silica powder. Furthermore, LFPs developed with NI‐1 were successfully lifted from different surfaces using adhesive tape for documentation and archiving purposes. To mimic the automated fingerprint identification system (AFIS), we manually screened fingerprints from 16 subjects to identify the unknown subject. The unique minutiae points such as long hook, opposite bifurcation, crossbar, cross over, dock, triple bifurcation, lake and spikes were observed beside other 16 minutiae points.

The Spin Measurement of MAXI J0637-430: a Black Hole Candidate with High Disk Density

The Galactic black hole candidate MAXI J0637-430 was first discovered by MAXI/GSC on 2019 November 2. We study the spectral properties of MAXI J0637-430 by using the archived NuSTAR data and Swift/XRT data. After fitting the eight spectra by using a disk component and a powerlaw component model with absorption, we select the spectra with relatively strong reflection components for detailed X-ray reflection spectroscopy. Using the most state-of-art reflection model, relxillCp, the spectral fitting measures a black hole spin a * > 0.72 and the inclination angle of the accretion disk i = degrees, at a 90% confidence level. In addition, the fitting results show an extreme supersolar iron abundance. Combined with the fitting results of reflection model reflionx_hd, we consider that this unphysical iron abundance may be caused by a very high-density accretion disk (n e > 2.34 × 1021 cm−3) or a strong Fe Kα emission line. The soft excess is found in the soft state spectral fitting results, which may be an extra free–free heating effect caused by high density of the accretion disk. Finally, we discuss the robustness of black hole spin obtained by X-ray reflection spectroscopy. The result of relatively high spin is self-consistent with broadened Fe Kα line. Iron abundance and disk density have no effect on the spin results.

Influence of Functionally Graded Protective Coating on the Temperature in a Braking System.

A mathematical model of heat generation due to friction in a disc-pad braking system was developed with consideration of a thermal barrier coating (TBC) on the friction surface of the disc. The coating was made of functionally graded material (FGM). The three-element geometrical scheme of the system consisted of two homogeneous half-spaces (pad and disc) and a functionally graded coating (FGC) deposited on the friction surface of the disc. It was assumed that the frictional heat generated on the coating-pad contact surface was absorbed to the insides of friction elements along the normal to this surface. Thermal contact of friction between the coating and the pad as well as the heat contact between the coating and the substrate were perfect. On the basis of such assumptions, the thermal friction problem was formulated, and its exact solution was obtained for constant and linearly descending specific friction power over time. For the first case, the asymptotic solutions for small and large values of time were also found. A numerical analysis was performed on an example of the system containing a metal ceramic (FMC-11) pad, sliding on the surface of a FGC (ZrO2-Ti-6Al-4V) applied on a cast iron (ChNMKh) disc. It was established that the application of a TBC made of FGM on the surface of a disc could effectively reduce the level of temperature achieved during braking.

Going deep: Excavation, collaboration and imagination at the Kola Superdeep Borehole

On the Kola Peninsula in the Russian Arctic lies an innocuous iron disc about the size of a dinner plate. If one were to prise this disc open, they would find the remains of the world’s deepest vertical hole. Reaching a depth of over 12 kilometres, the Kola Superdeep Borehole was drilled in the pursuit of excavating scientific knowledges for a better understanding of the Earth’s crust. Whilst the borehole produced some important findings, and hosted an international delegation of researchers, once the Soviet Union collapsed, it fell into disrepair. Since its closure, the Kola Superdeep has become lost to history, but its existence as a ruin has generated new artistic engagements with the underground. This article uses the geological notion of discontinuity – a structural break in the rock – to imagine how discontinuity might be found within the borehole itself. It does this by identifying three access points: excavation through drilling and coring, collaboration through cross-border scientific work, and imagination through art and the weird. By resisting the notion that the subterranean can be objectively known through science, I reveal how the Kola Superdeep produces other relations, knowledges, and ways of sensing the subterranean.

Friction, wear, and characterization of magnesium composite for automotive brake pad material

Magnesium metal matrix composites for lightweight brake pad applications are developed in this study. The composites are fabricated by using the powder metallurgy process. The addition of 0.5 wt.% to 2 wt.% Y2O3 (Rare Earth Oxide) used as a reinforcement to the AZ31 Mg composite is investigated. Density, hardness, and tribometer tests are carried out according to the ASTM standards. The friction and wear test of magnesium composites is tested against the grey cast iron disc. FESEM analysis shows the microstructure and morphology of worn surfaces. The elemental mapping result depicts that the elements of Mg, Al, Zn, Y, and O are uniformly distributed in the composite. X-ray diffraction analysis shows the compounds of Y2O3, MgO, ZnO, and Al2O4 are present on the worn surface of AZ31 + 2 wt.% Y2O3 composite. The outcome of the experiment reveals that increasing the proportion of yttrium oxide increases the magnesium composite's density and decreases the porosity. AZ31 + 2 wt.% Y2O3 composite exhibits the highest hardness of 122HV, a stable coefficient of friction, and a lower wear rate compared to AZ31 + 0 wt.% Y2O3 composite.

Life cycle assessment of carbon ceramic matrix composite brake discs containing reclaimed prepreg scraps

In the last years, carbon ceramic brakes are preferred to traditional cast iron ones for their lightweight, high temperature resistance, and long service life, even though their manufacturing involves the use of high temperature processes and energy-intensive materials such as carbon fibers. Within the European Life Project “CIRCE”, a novel recovery system for carbon fiber prepreg scraps was developed to reclaim high-quality carbon fibers to use as a substitute of virgin carbon fibers in different application, such as in Ceramic Matrix Composite (CMC) brakes. In order to overcome the lack of scientific literature regarding the environmental sustainability of steel and CMC brakes, in the present paper, the Life Cycle Assessment (LCA) methodology was applied to carry out a detailed analysis of the environmental impacts associated with carbon ceramic brakes realized using the reclaimed prepreg scraps. The functional unit was defined as production, use and disposal of a rear brake disc used for the deceleration of a sport car during its lifetime. Different impact indicators were considered, such as Global Warming Potential, Cumulative Energy Deman and ReCiPe midpoint categories. The results were compared to those given by the sustainability assessment of cast iron disc brakes and traditional carbon ceramic brakes. The proposed LCA is a cradle to grave analysis, as it considers all the relevant inputs and outputs of the manufacturing processes, from the raw material extraction to the materials disposal. The surface of ceramic brakes was observed using Scanning Electron Microscopy to assess the different material structures. The results show that, as far as the production is concerned, cast iron brakes are the most sustainable alternative, with impacts lower than 21% of the composite component ones. However, if a long use phase more than 200,000 km is evaluated, carbon ceramic brakes obtained by reclaimed prepreg scraps are characterized by lower environmental impacts, with impacts that are about 8% lower than those obtained by traditional carbon ceramic brakes.

Corrosion Stiction in Automotive Braking Systems.

This review paper targets the corrosion-stiction phenomenon that can occur in automotive braking systems under static conditions in aggressive environments. The corrosion of gray cast iron discs can lead to a strong adhesion of the brake pad at the pad/disc interface that can impair the reliability and performance of the braking system. The main constituents of friction materials are initially reviewed in order to highlight the complexity of a brake pad. Corrosion-related phenomena, including stiction and stick-slip, are considered in detail to discuss the complex effect of the chemical and physical properties of friction materials on these phenomena. In addition, testing methods to evaluate the susceptibility to corrosion stiction are reviewed in this work. Electrochemical methods, including potentiodynamic polarization and electrochemical impedance spectroscopy, are useful tools for a better understanding of corrosion stiction. The development of friction materials with low susceptibility to stiction should follow a complementary approach targeting an accurate selection of the constituents, control of local conditions at the pad-disc interface, and the use of specific additives or surface treatments to reduce the corrosion susceptibility of gray cast-iron rotors.

Quench hardening effect of gray iron brake discs on particulate matter emission

In this study, particulate matter produced during the braking of motor vehicles was investigated. In particular, this study focused on the effect of quench hardening of gray iron discs on brake emissions. The disc hardening effect was evaluated with commercial low-steel and non-steel brake pads using a 1/5 scale inertial brake dynamometer equipped with a particle counter. The results indicate that the disc hardening effect was significantly affected by the type of friction material due to different wear mechanisms. The low-steel brake pads produced more brake emissions when using the quench-hardened disc due to the increased aggressiveness of the hardened disc against the brake pad. In contrast, the hardened disc substantially reduced particulate matter emission when using the non-steel brake pads because the pad's surface became more wear-resistant due to the smaller amount of iron transferred from the hardened disc compared to conventional gray iron discs. These results suggest that the iron transfer from the disc to the pad's surface plays a crucial role in brake emissions.

Temperature Calculation, Test and Structure Improvement of Magnetic Coupling under High Slip

The temperature effect caused by high slip has an important influence on the operation performance and reliability of magnetic coupling. Taking the self-developed single disk asynchronous magnetic coupling as the research object, the heat loss equation of the magnetic coupling is established. Based on the three-dimensional transient magnetic field simulation model of the magnetic coupling, the eddy current loss, torque, and eddy current distribution law of the magnetic coupling are obtained through simulation. The space flow field and structure temperature field distribution of the magnetic coupling are analyzed by using the fluid-thermal coupling simulation method, and the heat dissipation coefficient and temperature distribution law of the structure surfaces such as copper disk, the back lining yoke iron disk, and the aluminum disk are obtained. The test platform was built to test the torque and temperature of the magnetic coupling. The results show that the error between the test and simulation is 4.8% in the torque aspect, and the maximum error between the test and simulation is only 8.1% in the temperature aspect of each component, which further verifies the effectiveness of the simulation method. On this basis, three heat dissipation improvement schemes are proposed, including installing heat dissipation blocks, setting semicircular grooves on the back lining yoke iron disk, and a hybrid design. The results show that the degree of improvement for each scheme is in the following order: hybrid design, setting semicircular grooves on the back lining yoke iron disk, and installing heat dissipation blocks. Under the hybrid design, the temperature of the back lining yoke iron plate and a copper plate of the magnetic coupling is reduced by about 8.5 °C compared with the original model, and the effect is ideal. The research results can provide an optimization reference for high-speed magnetic coupling and the temperature effect caused by an overload-locked rotor.

Interlaboratory Study on Brake Particle Emissions Part II: Particle Number Emissions

The Particle Measurement Programme (PMP) informal working group co-ordinated a global interlaboratory study (ILS) on brake wear particle emissions with the participation of 16 laboratories in 2021. Two articles present the results of the ILS: (I) particulate matter mass (PM) and (II) particle number (PN) emissions. The test matrix covered different brake systems, including ECE and NAO pad materials with grey cast iron discs and a drum brake. Regarding PN, the study measured the total particle number from approximately 10 nm to 2.5 µm (TPN). Some testing facilities measured solid particle number emissions (SPN) in parallel. The mean TPN concentrations ranged from 9.1 × 108 #/km/brake to 1.1 × 1010 #/km/brake. TPN and SPN emission levels were comparable, except for one lab that measured very high volatile particle emissions for one brake system. The minimum and maximum SPN emissions for a given brake differed by a factor of 2.5 ± 0.5, comparable to data from exhaust SPN ILS measurements. This article provides an overview of lessons learned and subsequent measures incorporated in an upcoming global technical regulation to reduce measurement variability when sampling and measuring brake particle emissions for light-duty vehicles up to 3.5 t.

Comparative Study on the Friction Behaviour and the Particle Formation Process between a Laser Cladded Brake Disc and a Conventional Grey Cast Iron Disc

Brake-wear particle emissions are the result of the components of a friction brake being in tribological contact, and they are classified as non-exhaust emissions. Since most of the emitted particles belong to the size classes of particulate matter (≤10 μm) and differ significantly in terms of their physico-chemical properties from automotive exhaust emissions, this source is of particular relevance to human health and, therefore, the focus of scientific studies. Previous studies have shown that coated brake discs offer significant wear and emission reduction potential. Nevertheless, no studies are available that describe the specific particle formation process, the contact conditions, the structure of the friction layer and the differences compared to conventional grey cast iron discs. The aim of this study is to describe those differences. For this purpose, the tribological behaviour, the structure of the friction layer and the associated particle dynamics within the friction contact between a laser cladding coated disc and a conventional grey cast iron disc are compared. The required investigations are carried out both ex situ (stationary) and in situ (dynamic). Parallel to the tribological investigations, the particle emission behaviour is determined on an inertia dynamometer using a constant volume sampling system (CVS) and equipment for particle number and particle size distribution measurement. The results show that, for two different brake pads, the laser cladding brake disc has lower wear and less particulate emissions than the grey cast iron brake disc. The wear behaviour of the coating varies significantly for the two brake pads. By contrast, the grey cast iron brake disc shows a significantly lower influence.

Study of the Influence of the Copper Component's Shape on the Properties of the Friction Material Used in Brakes-Part One, Tribological Properties.

Brakes play an extremely important role in any vehicle. In today's automotive industry, friction brakes are most often used, in which the composite material of the brake pad cooperates with a cast iron disc. While little can be modified in the case of discs, in the case of pads, the composition of the material used for its production can have an almost unlimited number of possibilities. Both scientists and manufacturers invent and test new combinations to achieve the desired end result. A similar task was undertaken in this work. Bearing in mind the fact that materials commonly used as reinforcing materials generate undesirable threats in the production process, it was decided to check whether this role could be taken over by another substance that is already present in brake pads; this substance is copper. A number of samples containing copper, in the form of powder and fibers, were made, and then the samples were subjected to tribological tests in order to determine the coefficient of friction and abrasive wear rate. The ball-cratering research method was used, and the Taguchi process optimization method was used to plan the experiment. As a result of the tests, it was found that the replacement of aramid fibers with copper fibers does not significantly affect the value of COF and the abrasive wear rate.

Modeling and Simulation of Brake Disc Using Lightweight Materials

Conventionally, Cast iron discs are used for brake discs. In the recent past, lightweight materials replace conventional materials in many vehicles to make them more fuel efficient. This work reports the results of the modelling and simulation of brake discs using five different materials. AISI6150, Cast Iron, Ti–6Al–4V, LM13 and Al SiC MMC were considered as brake disc materials. The temperature distribution, heat flux and thermal gradient of these materials were analysed and the results are reported. Al SiC MMC is found to have the lowest weight, distributes heat to a larger area for enhancing the heat dissipation, has a higher heat flux and a low thermal gradient.

The effect of external magnetic field on osteogenic and antimicrobial behaviour of surface-functionalized custom titanium chamber with iron nanoparticles. A preliminary research.

The controlled responsive characteristics of iron nanoparticles (FeNp) in magnetic fields make them an attractive prospect in this field. In the presence of a magnetic field, FeNp can significantly impact cell behaviour, leading to breakthroughs in nanotechnology. The aim is to determine the possible applications of iron nano particles (FeNp), and induced magnetic exposure role in osteoconduction and antibacterial activity. The custom-grade IV titanium (Ti)hollow chamber is fabricated, surface treated with FeNp. Each titanium chamber contained neodymium, iron, and boron magnet disc, and the effect of FeNp on osteoblast-like cells (MG63) was evaluated in terms of cell attachment and survivability, morphological characteristics, particle absorption, and antibacterial properties. The effects of cellular uptake of FeNp and their responses to subcellular thrust were studied using fluorescent microscopy. MTT was used to determine cell viability, and von Kossa histochemical staining was used to determine matrix mineralization. In the magnetized Ti chambers group, osteogenic activity and mineralization were considerably greater than in the control groups (p 0.05). With a p value of 0.027, the S. aureus and E. coli were resistant to the antibacterial properties of the FeNp modified titanium custom Ti chamber (MIC: 0.03135mg/mL and 0.02915mg/mL, respectively). The one-of-a-kind, in vitro, conveniently modelled, limited sample study sheds light on the effect of surface-functionalized titanium custom Ti chamber with FeNp on MG63. The use of magnetized FeNp-surfaced implants for long-term strategic bone tissue engineering and bacteriostatic implants.