Mechanical Resistance Properties Research Articles

Development of Cement Stabilised Compressed Blocks Using Coal Bottom Ash: Influence of the Grain Size on Mechanical and Physical Properties of Blocks

This study investigated the physical and mechanical properties of cement-stabilized compressed blocks manufactured with coal bottom ash sourced from a power plant in Niger. Three different grain sizes were used for the production of compressed blocks with a hand-operated press. Thermal, hydric, mechanical, and fire resistance properties were assessed on the samples. It was found that the use of finer bottom ash resulted in lighter blocks with a density of about 1.02 mg/m3 and thermal conductivity in the range of 0.27 – 0.41 W/m·K. The size of the bottom ash used for the production of blocks did not significantly affect the value of mechanical strength. The exposure of blocks to temperatures of 200°C and 400°C did not reduce the strength of the samples. Neat bottom ash blocks can offer better thermal properties than typical building materials and provide acceptable mechanical strength.

Precise role of zirconia to boost up the mechanical, thermal, viscoelastic, dielectric, and chemical resistance properties of natural rubber-nitrile rubber blend

Silica and other metal oxides have been emerged as potential substitutes of conventional carbon black (CB) to reinforce elastomeric materials. It not only steers clear of the ill-effects of CB such as issues like carcinogenicityand carbon footprint but they can impart rich thermal, optical, dielectric, and antimicrobial properties to the composites in addition to appreciable reinforcement. Silica is of special mention in this context while titania and zirconia to follow next. In this work, we report efficacy of zirconia towards property enhancement of a rubber blend comprised of non-polar natural rubber (NR) and polar nitrile rubber (NBR). Designed and controlled incorporation of zirconia in rubber matrix via an in-situ approach offers appreciable reinforcement to the composites. This is due to the fine dispersion of zirconia in elastomer matrix (SEM), efficient rubber-filler interaction (DMA) and increased crosslinking densities (swelling study). Analysis by atomic force microscopy (AFM) and differential scanning calorimetry (DSC) indicates that in-situ zirconia acts in favour of improved blend compatibility as well. All these factors offer notable impact on the other composite properties viz. improved thermal stability, enhanced flame retardancy and excellent chemical resistance to the blend composites. Additionally, dielectric properties become better upon incorporation of in-situ zirconia. The enhancement of composite properties becomes more prominent upon surface modification of in-situ zirconia by an organosilane Bis-(3-triethoxysilylpropyl) tetrasulfide (TESPT). Superiority of in-situ zirconia over externally filled zirconia has been established by a comparative analysis. Hence, current study offers valuable insights on the potential of in-situ zirconia as a substitute of CB to reinforce the rubber blends. The findings have important implications for the development of high performance elastomeric composites that can sustain in harsh service conditions.

Multi‐Objective Optimization During Magnetic Field Assisted ECDM of Alumina‐Zirconium Dioxide Ceramic Composite using Battle Royale Optimization

Alumina‐Zirconium dioxide (Al2O3‐ZrO2) Ceramic Composite Material (CCM) is specifically known for its enhanced mechanical and corrosion resistance properties and is widely used as raw material for mechanical parts like, pump components, die inserts, bearings, etc. As a result, industrialists are searching for an efficient method for machining this Al2O3‐ZrO2 material. In this regard, a hybrid unconventional machining process called Electrochemical Discharge Machining (ECDM) is adapted to analyze the machinability of Al2O3‐ZrO2 CCM. Besides, to ensure the efficiency of the ECDM process, a magnetic field is also given to the tool electrode during this study to improve the Material Removal Rate (MRR) of the ECDM machine. The experiment is designed using Response Surface Methodology (RSM) by changing the magnitudes of input controls, namely Electrolytic Concentration (EC), Inter‐electrode Gap (IEG) and Applied Voltage (AV). Moreover, a novel hybrid machine learning optimization strategy called Deep Belief Network based Battle Royal Optimization (DBN‐BRO) algorithm is developed to predict and optimize the ECDM process. Finally, the optimum results are perceived from 55 V AV, 22.727% EC and 40.909 mm IEG input levels. The proposed method shows less than 0.6207 Root Mean Square Error (RMSE) and tools nearly 80 iterations for optimizing the results.

Stretchable Clay Nanocomposite Barrier Film for Flexible Packaging

The goal of reconciling all packaging requirements, e.g., mechanical resistance, transparency, flexibility, and gas barrier properties, is immensely challenging for packaging materials. Particularly, the combination of flexibility and good gas barrier properties poses a serious problem, especially when barrier requirements can only be met by lamination with a metal foil, metalization, or vapor-deposited ceramic layers, as all of these tend to be nonstretchable. In this work, we produced a stretchable nanocomposite barrier composed of one-dimensional (1D) crystalline (Bragg stack) barrier films composed of alternating layers of poly(ethylene glycol) (PEG) and synthetic sodium fluorohectorite (Hec) nanosheets. By sandwiching the Bragg stack type film between two plasticized poly(vinyl alcohol) (PVOH) layers, a waterborne laminate was obtained that outperforms commercial polymer materials in terms of water vapor permeability (WVP = 2.8 g mm m-2 day-1 bar-1 at 23 °C and 85% relative humidity), which is remarkable for an entirely water-soluble film. Moreover, no deterioration of barrier performance up to 10% elongation was observed, rendering the transparent self-standing laminate promising for thermoformed blister packaging, shrink wrap, or vacuum packaging. Besides the low WVP, the scalable and green processing method makes this technology auspicious for real-world applications.

Simple Laser-Induced Hexagonal Boron Nitride Nanospheres for Enhanced Tribological Performance

Hexagonal boron nitride, as a layered material with a graphite-like structure, exhibits good mechanical, lubricating and oxidation resistance properties, and is thus expected to become one of the top choices for green lubricating oil additives. However, its poor dispersibility in oil and difficulties in preparing spherical particles when constructing hexagonal boron nitride limit its application. In this paper, spherical hexagonal boron nitride nanoparticles are constructed via a simple laser irradiation method. Under laser irradiation, raw irregular hexagonal boron nitride particles were reshaped into nanospheres via a laser-induced photothermal process and rapid cooling in a liquid-phase environment. Under the optimal concentration, the coefficient of friction and wear spot diameter decreased by 26.1% and 23.2%, and the surface roughness and wear volume decreased by 29.2% and 23.8%, respectively. The enhanced tribological performance is mainly due to the ball bearing, depositional absorption and repair effect of the spherical particles. This simple laser irradiation method provides a new method by which to prepare spherical hexagonal boron nitride lubricating oil additives.

Various HFCVD diamond coatings synergistically tuned using CH4 gas flow and working pressure and key merit evaluation of their coated tools

Diamond-coated tools can meet the service requirements of high precision, high efficiency and long life with multi-element coupling, but the milling characteristics of graphite materials with high spindle speed, feed speed and high force may require tools with a high number of micro-edges and good adhesion strength. In the present study, microcrystalline diamond (MCD), nanocrystalline diamond (NCD) and gradient composite diamond (GCD) coatings were deposited on commercial end mills subjected to distinct CH4 gas flows and working pressure by hot filament chemical vapor deposition. The adhesion strength, erosion resistance and milling performance of the diamond coatings in milling graphite materials were evaluated. Besides, the effect of CH4 gas flows and working pressure on the growth model of diamond coatings and the mechanism of crack propagation when subjected to stress concentration were studied. The results show that the combination of high CH4 gas flows and low working pressure achieves the re-nucleation of diamond particles, the smaller grain, more graphite/amorphous carbon in the boundaries and larger residual stresses lead to continuous crack propagation, causing poor adhesion strength, erosion resistance and milling performance in NCD and GCD coatings. Conversely, the low CH4 gas flows to ensure the epitaxial growth required for MCD coating, the larger grain, higher diamond purity, columnar structure and smaller residual stresses allow the pinning effect between coating and substrate, altering and increasing the path of crack propagation, making it suitable for milling conditions with high speed and high force. This study provides significant insights into the links between diamond morphology, structure, grain size, boundaries, and phase composition and the mechanical properties of adhesion strength, erosion resistance, and milling properties by synergistically tuning or alternating the CH4 gas flows and working pressure.

Metallurgical, mechanical and corrosion behaviour of pulsed and constant current TIG dissimilar welds of AISI 430 and Inconel 718

This research work explore the weldability, structural integrity, mechanical properties and corrosion behaviour of dissimilar welds of Inconel 718 and AISI 430 developed by using constant and pulse arccurrent modes in TIG welding process. The welded structures defects for inspected by employing X-ray radiography images as well as macrostructures. Metallurgical changes were observed using optical & scanning electron microscope techniques. Mechanical properties of the joined structures were evaluated by performing tensile test on UTM and hardness measurements on weld surfaces using Vickers hardness tester. The resistance against the corrosion especially at the weld area of both welded structures was measured. The joined structures were free from flaws and also seen the uniformity of the filler distribution towards the base metals. The grain coursing with well-defined grain structures were identified in CC-TIG weldmentswhereas fine grains with clear distribution of filler alloying elements were seen in PC-TIG weldments. PC-TIG weldments exhibited with better mechanical and corrosion resistance properties than the CC-TIG weldments vowing to pulse arc mode during welding process. The aerospace and nuclear industries will benefit from the study's findings especially turbine disc and shaft assembly.

Mechanical and Thermal Properties of the High Thermal Conductivity Steel (HTCS) Additively Manufactured via Powder-Fed Direct Energy Deposition

High thermal conductivity steel (HTCS-150) is deposited onto non-heat-treated AISI H13 (N-H13) via powder-fed direct energy deposition (DED) based on the response surface methodology (RSM) to enhance the mechanical properties and thermal conductivity of N-H13, which is generally used as a hot-work tool steel. The main process parameters of the powder-fed DED are priorly optimized to minimize defects in the deposited regions and, therefore, to obtain homogeneous material properties. The deposited HTCS-150 is comprehensively evaluated through hardness, tensile, and wear tests at the different temperatures of 25, 200, 400, 600, and 800 °C. Compared to conventionally heat-treated (quenched and tempered) H13 (HT-H13), the hardness of the additively manufactured HTCS-150 slightly increases at 25 °C, whereas it does not show any significant difference above 200 °C. However, the HTCS-150 deposited on N-H13 shows a lower ultimate tensile strength and elongation than HT-H13 at all tested temperatures, and the deposition of the HTCS-150 on N-H13 enhances the ultimate tensile strength of N-H13. While the HTCS-150 does not show a significant difference in the wear rate below 400 °C compared to HT-H13, it shows a lower wear rate above 600 °C. The HTCS-150 reveals a higher thermal conductivity than the HT-H13 below 600 °C, whereas the behavior is reversed at 800 °C. The results suggest that the HTCS-150 additively manufactured via powder-fed direct energy deposition can enhance the mechanical and thermal properties of N-H13, including hardness, tensile strength, wear resistance, and thermal conductivity in a wide range of temperatures, often superior to those of HT-H13.

Reversible imine crosslinking in waterborne self-healing polymer coatings

Waterborne polymer coatings have the potential to address the environmental concerns associated with solvent based systems. To improve their performance without using volatile organic compounds, we propose a new approach based on reconfigurable covalent crosslinking that provides mechanical resistance and self-healing properties. The new waterborne polymer coatings are based on mixtures of aldehyde- and amine-functionalized polymer nanoparticles (PNPs) that take advantage of the reversibility of imine bonds in the presence of water. Different degrees of functional monomer incorporation (10 % to 40 %) allowed us to balance crosslinking and interdiffusion during film formation, to obtain mechanically robust and solvent resistant films. A clear structure-properties relation was assessed by following the formation of water resulting from amine-aldehyde condensation crosslinking, measured by differential scanning calorimetry. The resulting polymer coatings further show self-healing properties at room temperature, triggered with residual amounts of water and featuring high recovery rates of the mechanical properties. Our mechanically robust waterborne polymer coatings based in imine reversible crosslinking, featuring self-healing in mild conditions, offer excellent prospects for application in smart coating materials.

Mechanical, thermal and CMAS resistance properties of high-entropy (Gd0.2Y0.2Er0.2Tm0.2Yb0.2)2Zr2O7 ceramics

A high entropy zirconate ceramic (Gd0.2Y0.2Er0.2Tm0.2Yb0.2)2Zr2O7 (HEZ) with fluorite structure has been synthesized by solid state reaction and high temperature sintering successfully. The investigation indicated that HEZ has ultra-low thermal conductivity (0.82 W × m−1 × K−1 at 1200 °C), similar thermal expansion coefficient (10.61 × 10−6 K−1 at 1300–1400 °C) with that of YSZ, excellent mechanical properties (hardness, elastic modulus, fracture toughness), and great CMAS corrosion resistance. Emphasis is given to discussing the CMAS wetting, corrosion process and failure mechanisms using high-temperature in-site wetting method and transmission electron microscopy (TEM). The results show that the HEZ exhibits better corrosion resistance than single rare earth zirconate Gd2Zr2O7 due to the coupling effect of anti-wettability, gradient diffusion rate and multicomponent apatite crystallization produced by doping rare earth ion (Gd3+, Y3+) close to Ca2+ radius and rare earth ion (Er3+, Tm3+, Yb3+) with small ion radii. In the comprehensive view, (Gd0.2Y0.2Er0.2Tm0.2Yb0.2)2Zr2O7 is a competitive candidate for high reliability TBC materials.

Process parameters and surface treatment effects on the mechanical and corrosion resistance properties of Ti6Al4V components produced by laser powder bed fusion

Process parameters and surface treatment effects on the mechanical and corrosion resistance properties of Ti6Al4V components produced by laser powder bed fusion

The use of herbal extracts in lacquer paint coloring and determination of some mechanical resistance properties on wood-based surfaces

The use of herbal extracts in lacquer paint coloring and determination of some mechanical resistance properties on wood-based surfaces

Impact of High Concentrations of Cellulose Fibers on the Morphology, Durability and Protective Properties of Wood Paint

This work aims to reveal the effect of a high amount of cellulose fibers on the durability and protective behavior of a bio-based wood paint. The influence of the filler on the morphology of the coatings was investigated by scanning electron microscopy observations, while the durability of the paint was evaluated by exposing the samples to UV-B radiation and continuous thermal shocks. Infrared spectroscopy analysis, colorimetric inspections, adhesion tests and scanning electron microscope observations were employed to assess the role of the high concentrations of fillers in affecting the resilience of the acrylic matrix. Moreover, the impact of the filler on the barrier performance of the coatings was estimated using a liquid resistance test and a water uptake test. Finally, the mechanical properties of hardness and abrasion resistance of the layers were evaluated by means of the Buchholz Hardness Indentation test and the Scrub test. Ultimately, this study demonstrates the pros and cons of using large amounts of cellulose fibers as filler in wood paint: the work warns against the excessive use of these fibers, which need a threshold limit so as not to significantly change the coating’s structure and thereby weaken its protective properties.

Curing Behavior of UV-Initiated Surface-Modified Nano-TiO2/Epoxy Resin Prepolymers and the Properties of Cured Composites.

Nano-titanium dioxides (nano-TiO2) surface modified with isopropyl tri(dioctylpyrophosphate) titanate (NDZ-201), a titanate coupling agent, and 3-glycidoxypropyltrimethoxysilane (KH-560), a silane coupling agent, were separately mixed with bisphenol A epoxy resin (DEGBA) prepolymer and then cured using a UV-normal temperature synergistic curing process. Then, the isothermal curing process of the system was investigated by differential scanning calorimetry (DSC). The relationship between the organization structures, mechanical properties, and heat resistance properties of the cured composites and material formulation was studied, and the DSC results showed that the addition of nano-TiO2 reduced the curing reaction rate constant k1 and increased the k2 of the prepolymer, while the activation energy of the curing reaction after UV irradiation Ea1 decreased, and the activation energy in the middle and later periods Ea2 increased. The characterization results of the composite material showed that nano-TiO2 as a scattering agent reduced the photoinitiation efficiency of UV light, and due to its obvious agglomeration tendency in the epoxy resin, the mechanical properties of the composite material were poor. The dispersibility of the coupling-agent-modified nano-TiO2 in the epoxy resin was greatly enhanced, and the mechanical and heat resistance properties of the composite material improved remarkably. The comparison results of the two coupling agents showed that NDZ-201 had better performance in increasing the impact strength by 6.8% (minimum value, the same below) and the maximum thermal decomposition rate temperature by 4.88 °C of the composite, while KH-560 improved the tensile strength by 7.3% and the glass transition temperature (Tg) by 3.34 °C of the composite.

Preparation and characterization of metastable β-type titanium alloys with favorable properties for orthopedic applications

Titanium (Ti)-based alloys with good mechanical properties are highly desirable for bone implants to achieve long-term clinical success. As non-toxic alloying elements, zirconium (Zr) and molybdenum (Mo) have been employed to improve the mechanical properties of Ti-based alloys. In this work, a series of Ti-Zr-Mo alloys, including Ti-18Zr, Ti-13Mo, and Ti-18Zr-13Mo were prepared and compared for potential orthopedic applications for the first time. The phase composition, microstructure, mechanical properties, corrosion resistance, biocompatibility, and osteointegration performance were systemically investigated. It is found that Ti-18Zr displayed an acicular α′ phase, whereas Ti-13Mo and Ti-18Zr-13Mo exhibited a metastable β phase. Compared with commercially pure Ti (CP-Ti), the prepared Ti-Zr-Mo alloys possessed a higher compressive yield strength and a greater microhardness, because of the solid solution and phase precipitation strengthening of Zr and Mo elements. Furthermore, Ti-18Zr-13Mo and Ti-13Mo demonstrated better corrosion resistance than that of CP-Ti, while Ti-18Zr exhibited an inferior result. The cytocompatibility and osteointegration of prepared alloys were similar to those of CP-Ti. Taken together, the Ti-Zr-Mo alloys investigated in this study present a promising alternative to CP-Ti for orthopedic applications, among which the metastable β-type alloy Ti-18Zr-13Mo is most attractive. Moreover, an appropriate Mo content enhances the mechanical and corrosion resistance properties of Ti-based alloys, whereas a high Zr content may pose an adverse influence on the corrosion resistance, which provides valuable insights into the design and further optimizing of new Ti-Zr-Mo alloys for future biomedical applications.

Enhanced Mechanical and Corrosion Properties via Annealing Treatment on the Hot-Rolled Ti-Zr-Mo Alloy

In this work, the Ti-20Zr-15Mo alloy in its hot-rolled state was annealed in different phase zones, and the effects of the annealing treatment on the phase composition, organization, mechanical and corrosion resistance properties of the alloy were systematically investigated. The results showed that the original β grains of the alloy had all recrystallized to form the β equiaxial grains when annealed at 800 °C, and the grains had been significantly refined. This allowed the alloy to reach a tensile strength of 1000 MPa, a maximum of 28% after stretching, and a significant increase in plasticity. Also, due to the single beta phase, there was no galvanic corrosion, making the alloy annealed at 800 °C have the best corrosion resistance.

Enhanced mechanical and water resistance properties of cassava starch-PVA composites with TiO2 nanofillers for triboelectric nanogenerators films

The utilization of biopolymers for energy applications continues to attract researchers, due to the unique properties of biopolymers that are easily modified, such as cassava starch (CS) biopolymer that has hydroxyl molecular chains. However, the brittle, and non-waterproof nature of starch films is an obstacle to their use in triboelectric nanogenerator (TENG) solid-solid films. This study aims to improve the physicochemical properties of cassava starch films by modifying them into nanocomposite films. The nanocomposite film was made from 70:30 CS/polyvinyl alcohol (PVA) composite and variation of TiO2 nanoparticles addition using solvent casting method. The results showed that the mechanical properties of cassava starch film increased with the addition of PVA. Meanwhile, the addition of TiO2 above 1 wt % of the mechanical properties of the film tends to decrease. The film has low wettability properties with a contact angle of 83.6°. The performance of the nanocomposite film as a Rotary disc freestanding film (RDF-TENG) produces 4.4-fold the output voltage and 2.8-fold the current compared to the film without TiO2. This is a new finding that the CS/PVA-TiO2 nanocomposite film has the potential for TENG films in high-humidity environmental conditions

Low Dielectric Constant Photocurable Fluorinated Poly (Phthalazinone Ether) Ink with Excellent Mechanical Properties and Heat Resistance

The photosensitive resins for 3D printing technology have been widely applied throughout the advanced communication field due to their merits of high molding accuracy and fast processing speed. Regardless, they, in particular, should have better mechanical properties, heat resistance, and dielectric properties. Herein, photocurable fluorinated poly (phthalazinone ether) (FSt-FPPE) was utilized as a prepolymer to improve the performance of photosensitive resin. A series of UV-curable inks named FST/DPGs were prepared with FSt-FPPE and acrylic diluents of different mass fractions. The FST/DPGs were cured into films by UV curing and post-treatment. After curing, their properties were characterized in detail. In terms of heat resistance, glass transition temperature (Tg) could reach 233 °C and the 5% thermal decomposition temperature (Td5%) was 371 °C. The tensile strength surprisingly reached 61.5 MPa, and the dielectric constant (Dk) could be significantly reduced to 2.75. Additionally, FST/DPGs were successfully employed in UV-assisted direct writing (DIW) to print 3D objects that benefited from their commendable fluidity and rapid curing speed. A stiff cylinder sample with a smooth surface and distinct pattern was ultimately obtained, indicating their remarkable 3D printing adaptation. Such photosensitive resin for UV-assisted DIW exhibits tremendous potential in the electronic industry.

Epoxy Primer Coating Filled Microcrystalline Cellulose Treated with Silane Coupling Agent on Metal Substrate

Epoxy resin was incorporated with microcrystalline cellulose (MCC) for the production of the primer coating. Various sonication times were applied for the purpose of determining the ideal sonication period that provides the best barrier performance. The coatings were also added with various 3-Aminopropyltriethoxysilane (APTES) loadings in order to improve the mechanical and corrosion resistance properties. Fourier Transform Infrared (FTIR) Spectroscopy analysis was carried out to examine the chemical interactions and diffusion between MCC, APTES, and epoxy resin. After nine days of immersion in a 5% sodium chloride (NaCl) solution, the ideal sonication period was found to be 30 minutes, with no corrosion occurring aggressively and no flaking or blistering appears on the coating. The anti-corrosive qualities of the primer coating were eventually enhanced by the addition of MCC modified with APTES. The addition of APTES had improved the interaction between MCC and epoxy, hence achieving better compatibility and promoting a uniformly dispersed MCC throughout the epoxy resin matrix. The Tafel polarization results found that the addition of APTES up to 9% gave the lowest corrosion rate at 0.004 mm/year and the highest polarization resistances at 198.69 kꭥ. This is explained by the fact that enough MCC-APTES can serve as a physical barrier and obstruct the paths used by corrosive agent to diffuse. Therefore, the MCC-Epoxy treated APTES coupling agent for metal corrosion protection has thus been successfully created.

Improved strength, creep resistance and recyclability of polyisoprene vitrimers by bottom-up construction of inhomogeneous network

Vitrimer elastomers bring huge chance to solve the recycling problem of conventional rubbers. However, their application is extremely limited by their lack of creep resistance. Although the crosslinking density can significantly affect the relaxation behavior of dynamic covalent networks, but limited by the tradeoff between mechanical strength and creep resistant properties. Here, we introduce inhomogeneous dynamic covalent network with regions of different crosslinking densities, in which the low crosslinking density mainly contribute to the creep resistance and the high crosslinking density contribute to the mechanical strength. In detail, block copolymers with polymyrcene and polyisoprene blocks and its control sample polyisoprene were prepared and epoxidized. The polymyrcene block is a double bond-rich block compared to polyisoprene block, which will become an epoxy group-rich block after epoxidation and a high cross-link density phase region after crosslinking with a dicarboxylic acid agent. Therefore, the cross-linked block copolymer will have an inhomogeneous dynamic covalent network, which were confirmed by the Multi-quantum (MQ) NMR tests, AFM images and tanδ measurement. And the heterogeneous structure becomes more obvious with the increased length of polymyrcene block. WAXD results show that cross-linked block copolymers have lower strain-induced crystallization onset strain and higher crystallinity, making them far stronger and tougher. In addition, block copolymer samples demonstrate lower creep and lower permanent set due to slow relaxation of the low crosslinking density regions. The recycling efficiencies of mechanical strength of block copolymer samples were higher than that of homopolymer. This work provides a useful approach for improving the mechanical properties and dimensional stability of vitrimer elastomers simultaneously.