Stable Friction Coefficient Research Articles

Tribological Properties and Corrosion Resistance of Stellite 20 Alloy Coating Prepared by HVOF and HVAF

This study examines the tribological and corrosion properties of Stellite 20 alloy coatings on F310H heat-resistant stainless steel that were prepared using HVOF and HVAF supersonic flame spraying techniques. To investigate the coatings’ microstructure, phase, microhardness, wear, and corrosion resistance, a range of characterization techniques, including SEM, EDS, XRD, microhardness, and friction wear-testers, weas employed. The results indicate that both HVOF and HVAF-prepared coatings exhibit a dense structure with porosity of 0.41% and 0.32%, respectively. The coatings are composed of γ-Co solid solution, ε-Co solid solution, Cr-rich solid solution, Cr7C3, WC, and CoCr2O4 phases. The microhardness of the Stellite 20 coatings prepared by HVOF and HVAF methods was 610 HV0.3 and 690 HV0.3, respectively, which is three times higher than that of the F310H stainless steel substrate. The wear mechanism of the HVAF coating is abrasive wear, while the wear mechanism of the HVOF coating is mainly fatigue wear with slight abrasive wear. The HVAF coating demonstrates superior wear resistance due to its higher flame velocity, denser coating, and higher average microhardness. In contrast, the HVOF coating shows a higher friction coefficient stability due to its lower hardness dispersion. The corrosion potentials of the HVOF and HVAF coatings are −0.532 V and −0.376 V, respectively, with corresponding corrosion current densities of 1.692 × 10−7 A·cm−2 and 6.268 × 10−7 A·cm−2, respectively. Compared to the HVOF coating, the Stellite 20 coating prepared using HVAF technology exhibits better wear and corrosion resistance.

A new strategy to improve the mechanical properties of CoCrNi medium-entropy alloys based self-lubricating composite in a wide temperature range

The fact that metal matrix is incompatible with hexagonal boron nitride (h-BN) seriously aggravates the mechanical and tribological properties of solid-lubricating composites. This study successfully introduces a solid-lubricant h-BN@Ag (Ag nano powders generated in-situ on h-BN surface). Adding h-BN@Ag to CoCrNi medium entropy alloys significantly improve the fracture toughness of the CoCrNi/h-BN (increased by 40.1%), which is resulted from decreasing porosity of the composite. In comparison with the CoCrNi/h-BN composite, obvious plasticity characteristics are found in CoCrNi/h-BN@Ag composite. Moreover, the composite containing h-BN@Ag exhibits a low, stable coefficient of friction (COF) in a wide temperature range (RT—600°C). Obviously, the COF of CoCrNi/h-BN@Ag composite is more stable than CoCrNi/Ag composite. Our findings show that adding h-BN@Ag is an effective way to enhance the fracture toughness and tribologicial behaviors of the CoCrNi matrix composites.

Effects of Nano-CeO2 on Microstructure and Properties of WC/FeCoNiCrMo0.2 Composite High Entropy Alloy Coatings by Laser Cladding

FeCoNiCrMo0.2 high entropy alloy has many excellent properties, such as high strength, high wear resistance, high corrosion resistance, and high ductility. To further improve the properties of this coating, FeCoNiCrMo high entropy alloy (HEA) coatings, and two composite coatings, FeCoNiCrMo0.2 + WC and FeCoNiCrMo0.2 + WC + CeO2, were prepared on the surface of 316L stainless steel by laser cladding technology. After adding WC ceramic powder and CeO2 rare earth control, the microstructure, hardness, wear resistance, and corrosion resistance of the three coatings were carefully studied. The results show that WC powder significantly improved the hardness of the HEA coating and reduced the friction factor. The FeCoNiCrMo0.2 + 32%WC coating showed excellent mechanical properties, but the distribution of hard phase particles in the coating microstructure was uneven, resulting in unstable distribution of hardness and wear resistance in each region of the coating. After adding 2% nano-CeO2 rare earth oxide, although the hardness and friction factor decreased slightly compared with the FeCoNiCrMo0.2 + 32%WC coating, the coating grain structure was finer, which reduced the porosity and crack sensitivity of the coating, and the phase composition of the coating did not change; there was a uniform hardness distribution, a more stable friction coefficient, and the flattest wear morphology. In addition, under the same corrosive environment, the value of polarization impedance of the FeCoNiCrMo0.2 + 32%WC + 2%CeO2 coating was greater, the corrosion rate was relatively low, and the corrosion resistance was better. Therefore, based on various indexes, the FeCoNiCrMo0.2 + 32%WC + 2%CeO2 coating has the best comprehensive performance and can extend the service life of 316L workpieces.

High temperature friction and wear of post-machined additively manufactured tool steel during sliding against AlSi-coated boron steel

In recent years, additive manufacturing (AM) of metallic materials has achieved the production of virtually fully dense parts, extending the range of potential applications. There is a growing interest in the use of AM to produce forming tools for hot stamping. The possibilities of locally tailoring the die material to tackle wear challenges and producing more complex geometries to improve die cooling are key-features driving that interest. However, there is a lack of knowledge concerning the tribological behavior of AM materials, particularly at high temperature, as well as the influence surface finishing processes after additive manufacturing. The aim of this study is to investigate the high temperature friction and wear behavior of a tool steel, produced by selective laser melting, within the context of hot forming of AlSi-coated boron steel. A high temperature strip drawing tribometer was used to perform sliding tests at 600 °C and 700 °C. Three different surface finishes were used for the AM samples: ground, milled and shot-blasted. A conventionally produced steel with the same chemical composition and a ground surface finish was used as a reference. At 600 °C, a similar stable coefficient of friction of 0.4 was observed for both materials and all surface topographies. At 700 °C, all tests resulted in a sudden increase in friction up to 0.9 due to local rupture of the AlSi-coating, severe material transfer and ploughing. The wear mechanisms observed for the ground surfaces, both AM and reference tool steel, were a combination of adhesive material transfer and abrasive material removal that promotes material pile-up, resulting in wedge formation on the tool steel surface. The characteristic wedge formation was not common in the milled surface. This is attributed to strain-hardening and topographical features from the finishing process. For the shot-blasted AM surface, deformation and flattening of the large asperities was observed, as well as material transfer. Subsurface deformation associated with high adhesion during sliding was observed, mainly for the ground surfaces. The milled surface resulted in the least amount of tool steel transfer onto the counter body, while the shot-blasted one resulted in the largest amount. AM and reference ground tool steel showed very similar friction and wear behavior in this tribosystem.

Thiadiazole functionalized covalent organic frameworks as oil-based lubricant additives for anti-friction and anti-wear

The thiadiazole functionalized covalent organic frameworks (COFs) were successfully prepared via polydopamine (PDA) as a connection layer. The fluorine-containing COF-F was synthesized via solvothermal reaction, which was subsequently wrapped with PDA layer via oxidative polymerization. Finally, the anti-wear agent thiadiazole dimer covalently bonded with PDA via the Michael addition reactions to obtain thiadiazole functionalized COFs (DTD@COF-F). The as-prepared DTD@COF-F exhibits good tribological properties as oil-based lubricant additives, representing a low and stable friction coefficient (0.104), and decreasing the wear volume by 67.8 % comparing to the base oil 500SN. The good lubrication performance mainly benefits from the robust protective tribo-film, while the anti-wear thiadiazole molecule functionalized COFs can absorb onto the friction pairs easily, hence play essential roles in its construction.

Friction and dry sliding wear of Al–Fe–Cr quasicrystals with multi-reinforcements by laser powder bed fusion

A specially designed Al–Fe–Cr alloy with a rapid solidification-induced multi-scaled heterogeneous composite structure was manufactured using a laser powder bed fusion (LPBF) process with a high relative density (over 99.7%) and defect-free features. From the aspect of a single molten pool, the LPBF processed sample presents three regions with distinct composite structures: i) inner laser fusion zone (LFZ); ii) molten pool boundary (MPB) and iii) heat-affected zone (HAZ). For instance, spherical Al–Fe–Cr quasicrystals with sizes ranging from 100 to 300 nm inside ultrafine cellular structures are observed in the laser fusion zone. In contrast, the molten pool boundary exhibits a microstructure containing coarse flower-like quasicrystal particles and rectangular θ-Al13(Fe, Cr)2-4 particles. Moreover, the finer reinforcements in the heat-affected zone are spherical, rectangular or structureless and disperse in the α-Al matrix. This heterogeneous structure can be attributed to the graded temperature and solidification rate inside a single molten pool during LPBF processing. The tribological performance of the QC-reinforced aluminum matrix nanocomposites was comparatively investigated on a ball-on-disc reciprocating tribometer (UMT Tribo), in which the coefficient of friction was recorded. The results show that the LPBF-processed sample presents a stable friction coefficient (0.548) from mild to severe loads with a higher wear resistance of 3.704 × 10- 4mm3/(N*m) than the other LPBF-processed Al alloys. The worn surface morphology analysis shows that the wear mechanism presents a duplex wear mechanism of adhesive and oxidation wear.

Preparation of the wear and corrosion-resistant coating using a composite process of laser surface texturing technology and plasma electrolytic oxidation

In this study, a composite process consisting of laser surface texture imitating fish scale shapes and plasma electrolytic oxidation (PEO) was used on the surface of aluminum alloy metals to prepare wear- and corrosion-resistant coatings. Before the conventional plasma electrolytic oxidation, the laser was used to prepare the imitation fish scale shape texture on the aluminum alloy surface. It was found that the PEO coating could cover the splash ablation particles left by the laser, while the imitation fish scale shape structure was enough to improve the tribological properties of the PEO coating, and the coating prepared by the combination of the two processes had a more stable friction coefficient, excellent corrosion resistance, and good resistance to abrasion corrosion. In this paper, the microstructure and composition of the coatings were characterized by metallurgical microscopy, XRD, and energy dispersive spectroscopy (EDS), and the protection mechanism and the physical model of the coatings prepared by the composite process were presented and discussed. In summary, the use of the composite process provides a feasible idea for improving the performance of aluminum alloys.

Influence of preload on the tribological performance of MoS2/GO composite lubricating coating

Lubrication is one of the key factors to ensure the reliable operation of sliding parts for some critical components in aerospace. The most favorable lubrication performance of the lubricating film is always achieved after the initial period or the pre-running-in period. In this work, the influence of preloads varying from 0.5 to 15 N on the tribological performance of molybdenum disulfide/graphene oxide (MoS2/GO) composite lubricating coating was studied. It was found that the coefficient of friction (COF) during the running-in period decreased from 0.17 at 0.5 N to 0.14 at 5 N, and stabilized at 0.14 with further increasing the normal load, indicated that the optimal stable COF was obtained at 5 N and negligible changes when load is further increased from 5 to 15 N. In contrary to the widely reported coatings that their tribological results deteriorate at high applied loads, the MoS2/GO composite lubricating coating here exhibits much lower COF under higher loads, with the COF decreased from 0.14 at 5 N to 0.03 at 100 N. The results suggests that the preload had a positive effect on the tribological performance of the MoS2/GO composite coating, the COF of the composite coating decreased with the increase of the preload, which further improved the tribological properties and even achieved the optimized lubrication condition, and the optimum preload was equal to or slightly higher than the steady-state load. This work provides a guiding idea for the selection strategy of the preload for optimal tribological performance of the solid lubricating coating.

Effect of the pin temperature and SiC reinforcement on dry sliding tribological behavior of aluminium based silicon carbide metal matrix composite (Al-SiC) using Taguchi approach

This paper deals with the replacement of existing brake pad material based on its highest strength and stiffness-to-weight ratio. To overcome this problem, we have investigated the input process parameters: silicon carbide weight percentage, normal pressure, sliding speed or distance, and temperature, all of which affect tribological properties. The tribological behavior of an aluminum-based silicon carbide metal matrix (Al-SiC) is investigated at elevated temperatures in this study. The metal matrix composite brake pad material has been introduced recently due to its cost-effectiveness, stable coefficient of friction, lower wear rate, and constant contact pressure at high temperatures. In this investigation, an LM25-SiC composite was fabricated using the stir casting technique, in which SiC particles were reinforced at 5%, 10%, and 15% by weight in the base alloy LM25. The investigation was carried out for friction and wear studies on a pin on a disc tester at elevated temperatures for different loads and sliding distances. The investigation using the design of experimentation highlighted by the Taguchi technique highlights the effectiveness of replacing existing brake pad material. The experimental results show improved mechanical properties due to the addition of SiC, and it is also observed that a 15% SiC addition to base metal gives optimal sliding wear.

Effect of Graphitization Degree of Mesocarbon Microbeads (MCMBs) on the Microstructure and Properties of MCMB-SiC Composites.

Mesocarbon microbead-silicon carbide (MCMB-SiC) composites were prepared by hot-press sintering (2100 °C/40 MPa/1 h) with two different graphitized MCMBs as the second phase, which exhibited good self-lubricating properties. The effects of the graphitization degree of the MCMBs on the microstructure and properties of the composites were investigated contrastively. The results showed that the composites that added raw MCMBs with a low degree of graphitization had excellent self-sintering properties, higher densities, and better mechanical properties; by comparison, the composites that added mature MCMBs with a high degree of graphitization, which has regular and orderly lamellar structures, not only had good mechanical properties but also exhibited a lower and more stable dry friction coefficient (0.35), despite the higher wear rate (2.66 × 10-6 mm3·N-1·m-1). Large amounts of mature MCMBs were peeled off during the friction process to form a uniform and flat graphite lubricating film, which was the main reason for reducing the dry friction coefficient of the self-lubricating composites and making the friction coefficient more stable.

Biodegradable cow dung for brake friction material: a preliminary investigation

The purpose of the study is to develop a biodegradable and non-asbestos/copper-free brake pad formulation. The possibility of using organic cow dung particles as an eco-friendly reinforcement in friction material for brake pads is investigated. Sodium hydroxide (NaOH) treated cow dung is Sun dried and ground to an average particle size of 200 microns. It is reinforced in epoxy resin in weight fractions of 5%, 10%, 15%, 20% and 25% along with other fillers and friction stabilizers. The composite samples are subjected to density, thermal conductivity, microhardness and tensile strength evaluation for mechanical characterization. Pin on disc testing is done to identify the coefficient of friction (CoF), wear coefficient and specific wear rate as a part of tribological characterization. The scanning electron micrographs and EDAX analysis of worn out surface is performed to study the wear mechanism. Promising results are seen with composite samples reinforced with 15% cow dung particles in terms of better microhardness, tensile strength, stable coefficient of friction and low wear. The investigation could guide industries working on brake pad materials. This could open up an era of low cost, organic and eco-friendly alternative to carcinogenic asbestos/copper in friction materials.

Effect of glass powder on the friction performance of automotive brake lining materials

In this study, bronze-based brake linings containing 0-8 wt% glass powder were manufactured by a hot pressing process and tribological properties of produced samples were investigated using a Chase-type friction tester. The hardness and density of the samples were also determined. The microstructures and friction surfaces of the samples were examined using scanning electron microscopy (SEM). As a result, it was dermined that the sample that was reinforced with 8 wt% glass powder has exhibited the best wear behavior. Furthermore, a reduction in the friction coefficient of all the samples with increasing friction surface temperature was observed. The results have showed that friction coefficient stability of the brake lining samples could be improved with the increasing content of glass powder.

Tribological Properties of Ti6Al4V Alloy Composite Texture Fabricated by Ultrasonic Strengthening Grinding and Laser Processing

The Ti6Al4V alloy has been widely used in aerospace equipment and medical devices. However, the poor wear resistance of the Ti6Al4V alloy hinders its further engineering application. In this study, the ultrasonic strengthening grinding process (USGP) and laser texturing process were employed to enhance the wear resistance of Ti6Al4V alloy. The frictional behavior of all samples was determined via a ball-on-disc friction and wear tester under dry conditions. The worn surface morphology, cross-sectional hardness, surface roughness, and microstructure were analyzed. The results demonstrated that the USGP induced high hardness, high dislocation density, and grain refinement, as well as improvements in the wear resistance of Ti6Al4V. Moreover, laser texture could enhance the capacity to capture wear debris and reduce wear probability. When combining the USGP and laser texturing process for the surface treatment of Ti6Al4V alloy, the lowest and most stable friction coefficients were obtained, as well as the best wear resistance. Compared to the polished sample, the steady stage friction coefficient of the sample treated by USGP and laser texturing process was remarkably decreased by 58%. This work demonstrates that combining the USGP and laser texturing process could be a promising solution for improving the wear resistance properties of Ti6Al4V alloy, which makes it more suitable for various engineering applications.

MXene/PFW bionic “sandwich” structure enables functional self-lubricating of wood-based composites

The terminal groups of Mxene have a strong affinity for polymers, giving them great potential for the synthesis of advanced lubricating fillers. In this paper, polytetrafluoro wax (PFW) was embedded between the layers of MXene to form MXene/PFW complexes which used as lubricating fillers and mixed with wood-based slurry. High-density poplar wood composites (HPW/MXene/PFW) were obtained via structural self-assembly in vacuum filtration process, which displayed the durable stability of friction coefficient (0.18) and lower volume wear rate [9.58 × 10−3 mm3/(N·M)] than pure wood-based materials [12.10 × 10−3 mm3/(N·M)]. It is mainly due to the strengthening effect of the lignin-cellulose cross-linked network and the synergistic self-lubricating effect of MXene/PFW, and else the introduction of MXene can make the self-lubricating transfer film more uniform, smooth and robust during the friction process.

Assessing the structural and morphological effect on the tribological characteristics of boehmite and alumina sub-microparticles

Materials based on aluminium oxide can be obtained in different crystalline structures, making them suitable for several industrial applications. Chemical stability and high wear resistance are interesting peculiarities when materials undergo severe mechanical and thermal solicitations, like in breaking events, where aluminium oxides are indeed widely employed like abrasives. Controlled particles size and morphology can affect materials intrinsic properties, then representing a chance when fine adjustments in terms of specific features are required. With this in mind, we obtained boehmite and alumina sub-microparticles with different structural and morphological features by changing the synthesis parameters. The tribological properties where then investigated, using steel as counterface in pin on disc configuration. Both families can be classified as abrasive materials, but friction behaviour appears significantly different. Bohemite samples display high and stable friction coefficient, arising from a stable tribolayer formation, apart when gibbsite presence is observed, since iron hydroxide formed on the steel counterface dramatically reduces the friction stability. The behaviour of alumina family appears strongly driven by structural features, although particles shape change during the sliding tests also affects the COF value and stability.

Steady superlubricity achieved by epoxy resin composite coatings containing polydimethylsiloxane

Epoxy resin (EP) coatings have been widely applied in the field of surface protection engineering due to their high adhesion and good corrosion resistance, but the high friction and low wear resistance of pure EP coatings restrain their service life. Developing superior EP coatings with superlubricity and good antiwear performance is extensively desirable but remains to be a challenge yet. Here we for the first time report a superlubricious epoxy resin composite coating containing polydimethylsiloxane, PDMS (EP/PDMS) prepared by a facile solvent evaporation method. The PDMS was found to self-aggregate into nanoparticles in the epoxy resin matrix and leaded to the enhancement of tensile toughness of the epoxy resin coatings. The composite EP coatings containing PDMS performed steady superlubricity and high wear resistance when sliding against different bearing materials. Especially, an exceptionally and stable low friction coefficient of 0.007 was achieved by rotationally rubbing on the EP composite coating with a small content of 3.0 wt% against silicon nitride (Si3N4) ball in ambient air with a high relative humidity of 70 %, and the average wear rate of the EP/PDMS composite coating was as low as 2.76 × 10−7 mm3/N·m in spite of its low hardness.

Rational Design of Mesoporous Silica (SBA-15)/PF (Phenolic Resin) Nanocomposites by Tuning the Pore Sizes of Mesoporous Silica.

The development of composite materials with functional additives proved to be an effective way to improve or supplement the required properties of polymers. Herein, mesoporous silica (SBA-15) with different pore sizes were used as functional additives to prepare SBA-15/PF (phenolic resin) nanocomposites, which were prepared by in situ polymerization and then, compression molding. The physical properties and structural parameters of SBA-15 with different pore sizes were characterized by N2 adsorption-desorption, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The thermal properties of the SBA-15/PF hybrid were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The mechanical, friction, and dynamic mechanical properties of SBA-15/PF nanocomposites were also studied. The results revealed that the pore sizes of SBA-15 have a significant effect on the resulting SBA-15/PF hybrid and SBA-15/PF nanocomposites. The thermal stability of the SBA-15/PF hybrid was dramatically improved in comparison with pure PF. The friction and dynamic mechanical properties of the SBA-15/PF nanocomposites were enhanced significantly. Specifically, the glass transition temperature (Tg) of the nanocomposite increased by 19.0 °C for the SBA-15/PF nanocomposites modified with SBA-15-3. In addition, the nanocomposite exhibited a more stable friction coefficient and a lower wear rate at a high temperature. The enhancement in thermal and frictional properties for the nanocomposites is ascribed to the confinement of the PF chains or chain segments in the mesopores channels.

Design and Pore Properties Tuning of Two‐Scale Porous Polyimide Fabricated by Isostatic Pressing for Improving Oil Storage and Tribological Properties

The development of smart lubricating materials with lasting lubrication and outstanding wear resistance while achieving speed response is of great significance in the field of bearing cage applications but has proven to be challenging. Herein, polyimide (PI) molding powder containing two kinds of PI with different rigidities is synthesized in situ to fabricate a two‐scale porous polyimide (PPI) by (cold and hot) isostatic pressing. The unique two‐scale porous structure originates from the bimodal particle size distribution of the PI molding powder. The oil stored in the two‐scale PPI is gradually thrown out as the rotation speed increases, which makes the two‐scale PPI suitable for bearing cages with a wider rotation speed range and realize persistent and stable oil supply under different speeds. The porosity of PPI decreases with increasing pressure during hot isostatic pressing, but the effect of temperature on the porosity is not obvious. Moreover, the two‐scale PPI maintains good mechanical properties, and its ring tension is as high as 22.3 MPa. Due to the high oil content (>15%) and excellent oil retention rate (93.3%, at 3000 rpm for 180 min), the two‐scale oil‐containing PPI exhibits a stable low friction coefficient (≈0.096) and ultralow wear rate (≈0.6810−6mm3 (Nm)−1).

The braking performance of pads for high-speed train with rigid and flexible structure on a full-scale flywheel brake dynamometer

The performance of two brake pads with rigid structure (Rigid pad) and flexible structure (Flex pad) were systematically compared and analyzed by braking test on a full-scale flywheel brake dynamometer. 109 brakes were conducted according to test program in China Railway Production Certification (CRCC) standard, including dry condition, recovering brake, static brake, wet condition, and continuous brake, as well as various clamping force to simulate the service of pad on the high-speed train from 50 km/h to 275 km/h of initial brake speed (IBS). Two pads displayed similar tendency of coefficient of friction (COF) when braking at IBS below 200 km/h under dry condition. However, the obvious fading and fluctuation of COF was detected on Rigid pad when the IBS was higher than 200 km/h, stability of COF was just 77%, lower than 91% of Flex pad. More severely, the total wear rate of Rigid pad was 0.13 cm3/MJ, which was 3 times more than 0.04 cm3/MJ of Flex pad. Nevertheless, Rigid pad presented more stable and higher COF under wet condition, and the minimum COF for Rigid pad was 0.262 when braking with 25 L/h of water flow, 2 times higher than 0.12 of Flex pad. All these differences attributed to the adjusting function of pad structure, which gave different contact status on rubbing surface. Flex pad contributed to an intimate contact status with brake disc during braking by adjusting friction elements, resulting in a uniform temperature distribution and stable COF. On the other hand, the intimate contact benefited to the formation of water film during wet braking, decreasing COF observably. This study provides useful information for the structural design of brake pad and braking control strategy for high-speed train.

Efficiency and Fatigue/Endurance Laboratory Tests of Aviation Friction Brakes

Abstract Brakes are one of the most important safety systems in moving vehicles and machines. In vehicles such as cars or motorcycles brakes are used for stopping, controlling speed, and sometimes changing direction of travel. In aircraft, the main function of brakes is to reduce landing speed. As landing is one of the most dangerous maneuvers in aircraft operation, brakes must be efficient and reliable in order to ensure safety of the crew, passengers, and cargo. The most efficient brakes nowadays are friction brakes where velocity is controlled by friction of a pair of specially designed materials, which ensure stable and high friction coefficient over the course of the required braking process. The process itself is the dissipation of energy during aircraft movement which generates very high temperatures in friction materials during the time of the braking process. The materials and the whole brakes have to be temperature resistant, and we must ensure braking parameters are stable during the whole process. The same principle relates to the endurance/fatigue of the brake assemblies which must be durable enough to survive as high number of braking cycles as possible without any failure, which can result in fatal consequences. Every friction pair and every newly designed brake assembly must be laboratory tested for efficiency and endurance/fatigue in order to be used in an aircraft or vehicle. In this paper, we present the basic set of laboratory tests in the scope of friction materials and brake assemblies. Results of the tests are used as confirmations/proofs of proper and safe operation of the brakes for use in vehicles, especially in aircraft but also in land-based vehicles.