Armor steels are widely used in both civilian and military applications, and they play an important role in protecting infrastructure due to their capacity for defense against a variety of threats. Welding is a typical method of joining armor steel plates in structures. The welding process affects the mechanical properties and performance of steel. This study aims to research the corrosion and wear behavior of welded armor steels, considering both the pre- and post-fatigue conditions. The effect of weld penetration rate, which varies with welding parameters, on the fatigue, wear, hardness, and corrosion properties of steel is investigated. To determine how fatigue affected corrosion and mechanical properties the specimens were tested before and after the fatigue test. Hardness values ranging from 200 to 500 HV were recorded along distinct hardness lines. Following the fatigue test, corrosion rates increased by 11

In this study, the effects of Cu matrix morphology and Cu-coated SiC reinforcement ratio on the microstructure, mechanical, and electrical properties of Cu-SiC composites were investigated. Dendritic and flake morphologies were used as Cu matrix morphologies, while Cu-coated SiC particle ratios were selected as 5, 10, and 20% by volume. FESEM/EDS and XRD analyses confirmed that the surface of the SiC particles was homogeneously coated with Cu. This strategy was taken to enhance the matrix-reinforcement interface and achieve a more compact composite. Results show that matrix morphology is an important factor in the performance of the composites. Composites of flake Cu matrix have demonstrated increased relative density (90.96 vs. 87.82%), hardness (~ 135 vs. ~110 HB), tensile strength (~ 252 vs. 177 MPa), and electrical conductivity (88% IACS vs. 75% IACS) compared to composites of dendritic Cu matrix. The flake Cu matrix composite containing 10 vol% Cu-coated SiC reinforcement showed the most stable performance in terms of mechanical and electrical properties. In this context, this composite was shown to be a scalable and high-performance material candidate for the field of electrical materials.

This study investigates the sustainable production of high-purity copper powders obtained from recycled scrap copper sheets through the electrolysis method. With increasing environmental concerns and the growing need for resource efficiency, recycling-based copper powder production has emerged as an attractive and sustainable alternative to conventional production methods. The study aims to optimize electrolysis parameters affecting powder morphology and properties in order to enhance the industrial applicability of the material. The Taguchi method was applied to optimize current density, solution concentration, and electrode distance, focusing on their effects on average particle size and apparent density. An orthogonal array design and ANOVA analyses were employed to identify optimal processing conditions. Material characterization was performed using scanning electron microscopy (SEM), laser particle size analysis, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The synthesized dendritic copper powders were grouped by average size (21.61 mu m, 52.24 mu m, and 87.97 mu m) and subsequently densified by hot-pressing to evaluate their physical, mechanical, electrical, and thermal properties. Samples with an average size of 52.24 mu m exhibited the best overall performance, achieving 98.5 % IACS electrical conductivity, 386 W/m & sdot;K thermal conductivity, 94 HB hardness, and 137 MPa tensile strength. The results demonstrate that recycled electrolytic copper powders can achieve high performance levels while simultaneously supporting sustainable production practices and improved industrial efficiency.

At particle-level engineering, this study mainly focused on the issues of microstructural heterogeneity and the high oxidation susceptibility of Cu-Al-Ni shape memory alloys (SMAs) suitable for high-temperature actuation. Initial powders of Cu (82-83 wt.%) and Al (14-15 wt.%) were first milled mechanically and the Cu-Al particles were modified using an electroless Nickel (Ni) coating process to achieve a controlled Ni enrichment of 4-5 wt.%. The SEM-EDS, XRD, and TGA findings reveal that the cryogenic milling effectively reforms dendritic Cu and spherical Al particles into a refined composite structure. This process resulted in particle size reduction from 40-70 & micro;m to 5-20 & micro;m, and apparent density values increased from 3.45 g & centerdot;cm-3 to 4.10 g & centerdot;cm-3. Microstructural investigations showed that the continuous Ni layer, without generating unwanted intermetallic phases, was obtained with the help of an electroless coating process. In addition, it was confirmed that the crystallite size decreased from 52.10 nm to 41.71 nm. Additionally, the oxidation of nickel-coated and cryogenically milled powders occurred at temperatures above 350 degrees C owing to the formation of a protective surface layer. In other words, these powders exhibited higher thermal stability. Consequently, this dual processing procedure represents a very useful method for changing particle shape and interfacial composition. These combined methods can help to create a powder structure with a composition optimum for the making of high-performance Cu-Al-Ni SMAs.

Overcoming heat management bottlenecks via surface engineering rather than internal additives, this study utilizes a Cu/Ag armor to transition heat transfer from slow phonon diffusion to ultrafast free-electron conduction, achieving unmatched thermal conductivity without sacrificing phase-change encapsulation. Expanded graphite (EG) matrices, encapsulated 93% paraffin wax (PW) by weight, were coated with a thick Cu shell (electrolytic) and then a thin Ag film (electroless). Results of characterization confirmed that the EG/ PW@Cu@Ag composite developed by the experiment raised the thermal conductivity of pure PW from 0.21 W/ m & sdot;K to a record 43 W/m & sdot;K, which indicated that, although the conductivities increased greatly, the latent storage of heat in the system (199.6 J/g) of material was maintained overcoming the trade-off problem. Due to the Ag layer the passivation of Cu surface occurred and demonstrated that the chemical structure is not changed even in 500 melt-freeze cycles with a negligible enthalpy loss at 3.6%. Infrared thermography confirmed the ultra-fast heat dissipation of the Cu - Ag armor, accelerating early-stage heat spreading (from 42.4 degrees C to 51.1 degrees C at 60 s) while ultimately capping the peak surface temperature at 70.1 degrees C (120 s) to suppress localized overheating. Therefore, the composite developed in this work provides a competitive and environmentally friendly candidate for application in thermal control of electric vehicle battery pack and next-generation high-power electronic systems due to its high energy density and best heat transfer rate.

Glass fiber-reinforced polyamide 66 (PA66-GF) composites are widely used in critical applications such as plastic firearm frames owing to their low density, favorable mechanical properties, and relatively high tribological resistance. However, long-term exposure to UV radiation, humidity, and temperature fluctuations can significantly degrade the surface and fiber-matrix interface, thereby reducing performance and service life. As such, increasing the natural weathering resistance of PA66-GF composites is imperative. In this study, it is tested whether a plasma-assisted Ceramic Coating (Cerakote) process improves protection from environmental degradation. The uncoated samples withered after approximately 3 months and showed microcracks, matrix degradation, and oxidation, whereas the coated samples showed no critical microstructural changes over the aging stage. The mechanical characterization demonstrated the coating was advantageous; at 3 months postcoated aging both coated and uncoated samples demonstrated a tensile strength of 80 MPa and 66 MPa respectively, an enhancement of above 20%. At six and nine months of aging, this pattern persisted. In addition, the coated samples exhibited approximately 50% higher wear resistance than the uncoated samples after 3, 6, and 9 months of aging.

Armor steel is widely used in various industries due to its exceptional yield strength and hardness. However, the cutting processes employed to shape these materials, such as laser and waterjet cutting, may exert a substantial influence on the fatigue resistance of the end product. Fatigue strength is a critical property in materials science, particularly when it comes to high strength steel. As industries strive for lighter and more efficient structures, the demand for materials with superior fatigue resistance becomes paramount. In this article, it is aimed to investigate the effects of laser and waterjet cutting processes on the fatigue strength of armor steel based on experimental results, highlighting the implications for structural integrity and performance. The samples cut by water jet and laser cutting processes were subjected to fatigue tests with and without anti-buckling apparatus. Fatigue tests were carried out at least four different stress values and S-N diagrams were created for 4 different situations. As a result of this study, it was determined that the fatigue strength of samples obtained by laser cutting method is lower than that of waterjet cutting samples. Additionally, it was observed that the fatigue strength of the samples using anti-buckling apparatus was higher.

This study involves the production of HEA materials using low-temperature and high-pressure principles by mechanical-alloying AlCrCuFeNi high-entropy alloy powders, followed by electroless Ag coating for enhanced interface properties and hot-pressing without additional sintering. The Ag interface significantly improved the bonding of HEA powders. While increasing temperature causes a 10% weight gain due to oxidation in HEA samples, this rate is only 1.5% in those produced with Ag-coated HEA. The Ag interface improved the hardness of the HEAs by 50%. The wear rate was reduced by more than twofold due to the Ag-interfaces. Ag exhibited a self-lubricating effect due to the Ag layers that repeatedly emerge during sliding, resulting in a low friction coefficient of 0.19 and excellent wear resistance.

Armor steels are crucial for their high hardness and toughness, providing protection in military and security applications, including vehicles and personal body armor. This study aims to assess the fatigue strength of welded armor steels having different weld penetration. Weld fusion or penetration (FOP) is an important issue in terms of welded joint strength. Especially in non-load carrying joints, how the fatigue strength will change with the increase in weld FOP can only be determined by the tests to be performed. In this context, the joint type was chosen as a non-load carrying cruciform joint in this study. Weld FOP is determined in terms of length in many studies. In this study, these values were evaluated in terms of unit of area as well as length. In addition to the experimental fatigue studies, specimens having different weld FOP rates were modeled and hot-spot stress analyses were performed by ANSYS workbench. As a result of the studies, a decrease in fatigue strength was determined by the increase in the weld FOP rate. The analysis revealed that as FOP rate increased, the hot-spot stress values became closer to the nominal stress.

This study was conducted to comprehensively investigate the effect of mechanical milling parameters on the properties of electrolytic pure copper powders and hot pressed billets fabricated from recycled copper wastes. Three different milling speeds, five different milling times and three different ball to powder weight ratios were used to fully reveal the effect of the mechanical milling process on the properties of recovered Cu powders. The results show that as the milling time and milling speed increased, the initial dendritic morphology of the copper was transformed into a flake-like structure. At 400 rpm and a 5:1 BPR parameters, the average particle sizes of C3, C4, and C5 after 2, 4, and 8h were similar to 52 mu m, 83 mu m, and 71 mu m, respectively. This suggests that particle size initially increases due to shape change and cold-welding, but at longer durations, fracture becomes dominant. The I5 with d(0.5) = 69.32 mu m exhibited a high flow rate of 5.88 g/s with an apparent density of 2.9 g/cm(3).While the hardness value of the Cu samples (A1-bulk sample) produced by exposure to the lowest deformation during the mechanical milling is 95.02 HB, the hardness value of the Cu specimens (F5-bulk sample) showing the highest apparent density, best flow rate and highest density values is 109.31 HB. The electrical conductivity values were determined to be approximately 52.2 MS/m, 57.4 MS/m and 44.3 MS/m for A1-bulk, F5-bulk and H5-bulk, respectively. This study offers valuable insights into the relationship between milling parameters, powder characteristics, and final material properties.

Reinforcing materials used in the production of metal matrix composites are used to improve the properties of the final composite. However, the compatibility between matrix and reinforcement and the reinforcement ratio directly affects the properties of the composite material. For this reason, low reinforcement ratios are preferred in many studies on ceramic particle reinforced composites. Unlike conventional studies, in this study, the effects of 10 wt%, 20 wt% and 40 wt% SiC content on the microstructure, dry wear properties and corrosion properties of Al2024 matrix composites were investigated. θ phase content became higher as the SiC content was increased. Hardness values increased with increasing SiC reinforcement. The highest value (307.68 HB) was obtained for the composite with 40 wt% SiC reinforcement, an increase of more than 100%. A decrease in volume loss with increasing SiC reinforcement was observed in the friction and wear tests. For 5 N of load and 1200 m of sliding distance, it was found that an addition of 40 wt% of SiC particles in Al2024 matrix results decrease in volume loss by almost 722%.

It is aimed to examine the effect of welding parameters on cruciform welded joints. Armor steels are used in military applications such as tracked and wheeled armored vehicles. These steels are quenched and tempered steels and have high yield stress and hardness. Although the increase in carbon equivalent increases the ballistic level together with the hardness value, weldability decreases. Therefore, the welding parameters of these steels must be determined carefully. Before the welding, chemical analysis, macro examination, hardness test, tensile tests and ultrasonic examination were carried out to verify the material properties. After the verification tests, plates were welded with three different welding parameters to observe the changing of the mechanical properties. After the welding process, welded pieces were subjected to non-destructive tests to inspect the weld imperfections. After the inspection, welded specimens were subjected to hardness test, macro examination and tensile tests. In addition to these tests, weld penetration (WP) measurements were performed with a new assessment method. In this measurement method, unit of area takes into consideration instead of the unit of length. As a result, it is determined that with the increasing welding parameters although WP increase, hardness values in heat affected zone decrease.

In this study, the microstructure, hardness, tensile strength, and dry wear properties of the cast AlSi10Mg alloy as well as the effects of processing parameters on the oxidation behavior of this alloy were investigated. In this context, AlSi10Mg (wt

Novolac matrix composites are crucial due to their exceptional resistance to heat, chemicals, and mechanical stress. These advanced materials find applications in aerospace, electronics, and automotive industries, providing high-performance solutions for components requiring superior durability and reliability. In this context, the microstructure, thermal, phase, and mechanical properties of the composites obtained as a result of the recycling-oriented reinforcement of the waste candle-soot (CS) reinforcement at the rate of 1 wt% to the pure novolac (PN) and shaping with the hot press method were examined in detail at first time in the literature. While microstructural properties and fracture mechanisms were investigated by scanning electron microscopy (SEM), thermal properties were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results obtained provided critical findings as the composite hardness, tensile strength, and flexural strength values were 3.28, 2.47, and 3.21 times higher than PN, respectively. CS-reinforced novolac composites made a significant contribution to the literature by introducing a novel and eco-friendly approach to enhance material properties. Their use as a filler material provided insights into sustainable novolac composites, offering potential applications in various industries, such as electronics and aerospace, with improved mechanical and thermal properties.

This study was mainly performed in order to examine the properties of electric motor brushes (EMB). EMBs are electrically conductive and work under wear conditions due to direct contact with the moving part (rotor) of electric motors. In accordance with the scope of the study, EMB characteristics were investigated in two different groups and reproduced with a new technique at the end of this phase. New EMBs were produced via varying proportions of copper matrix, graphene, and silicon carbide reinforcements. The composite-alloy powder elements were carefully squeezed by a cold and single-axis hydraulic press under a pressure of 500 MPa (±5 MPa) following 8 hours of mechanical alloying (MA). The molded composite product (sample) was sintered at 900° C for 1 hour in a reducing gas atmosphere. 100 kPa spring pressure was tested on each sample thrice with 8, 16, 24, and 32 m/s rotational speeds and densities of 4, 8, 12, and 16 A/cm2. Following this process, the electrical conductivity, porosity, hardness, wear loss, surface roughness, and temperature changes were investigated for each sample. It was determined that the electrical conductivity decreased with increasing reinforcement ratio and, in terms of electrical conductivity, affected the brushes’ properties negatively.

This study extensivelyinvestigatesthe effectsof 10 wt% graphitereinforcementand varyingB4C content(1 wt%,2 wt%, 4 wt%) on the propertiesof Novolacmatrixpolymercompositespreparedby mechanicalmilling-assistedhot pressing.The microstructures,wear surfaces,wear debris,and fracturesurfacesof the producedpolymercompositeswere examinedusingSEM and EDS. The densitymeasurementswere conductedaccordingto theArchimed's principle.Their tribologicalbehaviorwas evaluatedwith a reciprocatingball-on-flatslidingwear testat 50 N, 75 N, and 100 N loads.After the wear tests, surfacetopographywas analyzedin 3D with an opticalprofilometer.The resultsindicatedthat compositeswith 2 wt% B4C had the lowestspecificwear rate and thehighestwear resistance

Flame-retardant properties are particularly important for materials used in high-temperature applications. This study focuses on novolac matrix composites reinforced with expandable graphite (EG) particles, produced through a hot pressing process using powders prepared by mechanical milling. The research examines the particle size of both the matrix and the reinforcing particles used in composite production. Additionally, the morphology of the powders, the microstructural properties of the composites, and the fracture surfaces after tensile testing were analyzed using scanning electron microscopy (SEM). Phase analysis of the samples was performed using X-ray diffraction (XRD). Hardness and tensile tests were conducted to evaluate the mechanical properties. The effect of EG particles on the thermal stability of the composites was assessed using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and thermal conductivity tests. Furthermore, flammability was evaluated by determining the Limit Oxygen Index (LOI) values. The experimental results identified the optimum reinforcement ratio as 20 wt% EG. TGA results showed residue values of approximately 37.39 % for pure novolac and 57.87 % for novolac matrix composites reinforced with 20 wt% EG. The highest thermal conductivity (0.72 W/mK) and LOI values (40.64 %) were achieved with 20 wt% EG reinforcement, resulting in an LOI value approximately 1.25 times greater than that of the pure novolac sample (32.45 %). Additionally, tensile strength increased by approximately 2.7 times compared to the pure novolac sample. This research highlights the potential of the novolac/EG composites for advanced high-temperature applications where enhanced flame retardancy and structural integrity are essential.

This study extensively investigates the effects of 10wt% graphite reinforcement and varying B4C content (1wt%, 2wt%, 4wt%) on the properties of Novolac matrix polymer composites prepared by mechanical milling-assisted hot pressing. The microstructures, wear surfaces, wear debris, and fracture surfaces of the produced polymer composites were examined using SEM and EDS. The density measurements were conducted according to the Archimed’s principle. Their tribological behavior was evaluated with a reciprocating ball-on-flat sliding wear test at 50N, 75N, and 100N loads. After the wear tests, surface topography was analyzed in 3D with an optical profilometer. The results indicated that composites with 2wt% B4C had the lowest specific wear rate and the highest wear resistance.

In this study, definitions of Weld Penetration (WP), Depth of Fusion (DOF) and Throat Thickness (TT) in fillet welds according to related standards are evaluated. Each standard makes its own definition related to WP, DOF and TT. Moreover, when looking at these standards, it is seen that definitions are always made in terms of unit of length. In many studies, assessment of fusion or penetration (FOP) rate on fillet welds is performed as the ratio of the maximum FOP depth to the material thickness. Depth assessment taking into consideration unit of length is not ideal for accurate evaluation of FOP rates especially on fillet welds. In the evaluation made in terms of unit of length, FOP rate can be approximately 50 percent more than the evaluation made in terms of unit of area. Method taking into consideration unit of area will be more suitable as it allows accurate assessment of FOP rates in welded joints. In this review, in addition to evaluation of the definitions of standards, it is also suggested that the evaluation of FOP rate on fillet welds should be determined in terms of unit of area rather than length.

Within the scope of this study, silicon carbide (SiC) and hexagonal boron nitride (h-BN) powders were added as reinforcement into zinc-aluminum (ZA40) matrix powders, and the powder metallurgy (PM) method, which is an advanced technique in material production, was used to fabricate ZA40/SiC/h-BN hybrid composites. In the milling process, the as -received powders were mechanically milled at 400 rpm under a protective argon atmosphere for 2 h at room temperature. The hybrid composite powders were consolidated under 700 MPa pressure at 515 degrees C for 3 h by hot pressing. Weight losses, friction coefficients, and wear rates were calculated by traveling 100 and 200 m at 250 rpm in a ball-on-disc abrasion test setup under 5 and 10 N loads. According to the results, it was seen that SiC and increased h-BN reinforcement changed the mechanical and physical properties of the composites and made significant contributions to the wear resistance and load-carrying capacity.