Glass-reinforced Epoxy Research Articles

An investigation of clay percentage variation on composite materials sustainability identification by digital image correlation

ABSTRACT The study focuses on stress and strain evaluation of composite resin material with the reinforcement of clay in the glass-reinforced epoxy composite (GREC). The strain measurement used the DIC technique. The tensile test specimens were prepared from the laminate sheets as per ASTM D638 standard. The influence of nano clay weight percentage such as 2.5%, 3.5%, and 4.5% during preparation of GREC is studied in the article. The fibre orientation angles are 90°, and the fibre volume percentage is 45%. Hand lay-up methods are used to prepare the composite resin material. The samples were tested as per the standardised procedures. The specimen rupture at a localised strain reached a maximum value of 0.01293, 0.01571, and 0.0143 with 2.5%, 3.5% and 4.5% Nano clay, respectively. The material behaviour in terms of major strain (εyy), Poisson’s ratio (µ) and thickness strain (Δt) is evaluated at the gauge length of the specimen. DIC strain measurement clearly demonstrates the 3.5% percentage of clay addition as it yields better results as elastic modulus and tensile strength have improved. The composite resin with clay addition could be used in various applications, such as low-cost housing, structural works, medical devices, automotive panels, etc

A Novel Investigation on Microstructural Analysis of a Rupture GRE Composite Pipe for Underground Fire Water System

This study investigates how underground fire water systems using Glass Reinforced Epoxy (GRE) pipes are affected by aging. Over time, GRE pipes can degrade, potentially reducing their expected lifespan. The study compared damaged and undamaged areas of pipes to assess how damage impacts their structural integrity. Microscopic and chemical analyses (SEM and EDX) were performed on pipe samples from different locations of the pipe. Mechanical testing (following ASTM standards) was conducted beforehand. Analyses revealed that as damage increased (closer to damaged area), the levels of carbon (C) and oxygen (O) changed significantly with the weight percentage exposed 45.62% difference and 11.62% difference, respectively, as compared with the undamaged area. This suggests that the epoxy resin degrades with age, releasing these elements. Additionally, the presence of foreign objects around the pipes can affect how they bear loads. These findings highlight the importance of understanding how aging and surrounding conditions can influence the performance of GRE pipes in real-world fire water systems.

Multi-objective optimization through desirability function analysis on the crashworthiness performance of thermoplastic/thermoset hybrid structures

This paper aims to optimize the crashworthiness capability of glass-reinforced epoxy composites (GFRE) over wrapped polyvinyl chloride (PVC) circular tubes with cutouts. The intended tubes were prepared by a wet wrapping method; then subjected to quasi-static axial compression. To compute crashworthiness indications, three design parameters, each at three levels, were used. The design parameters are the hole diameter (d), the hole's number (n), and the hole position (L). A few runs were accompanied by the L9 orthogonal array based on the Taguchi technique. With the lowest initial peak crash force (Fip) and the largest absorbed energy (U), the optimal parameters were found. Furthermore, the main effect, signal-to-noise ratio (S/N), as well as the analysis of variance (ANOVA), have been studied using the commercial software program MINITAB 18. Furthermore, to optimize the process parameters in terms of the crashworthiness indicators, desirability function analysis (DFA) was applied. Lastly, tests for confirmation were performed to verify the predicted values in light of the experimental results and compare them with the intact tubes. Regarding the single optimization, the optimum Fip tube is smaller than the intact PVC tube and intact hybrid tube, at 24.01 and 72.85 %, respectively. Nonetheless, the optimal U was 21.43 % lower than the intact hybrid tube and 152.75 % greater than the intact PVC tube. While, for Fip and U, the multi-objective optimization specimen achieves 5.13 and 70.02 % greater than the intact PVC tube. But it was 62.44 % and 47.14 % less than what the intact hybrid tube had accomplished.

Nonmetallic-Based Tubulars Provide Superior Integrity, Cost Savings

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 214647, “Operational Experience From the Implementation of 21 Wells With Nonmetallic-Based Downhole Tubing: From Pilot to Large-Scale Implementation,” by Mohamad H. Ahmad, ADNOC. The paper has not been peer reviewed. _ Tubular glass-reinforced-epoxy (GRE) lining technology has been applied globally since the 1960s in eliminating downhole tubular corrosion. Compared with conventional carbon steel, which can experience frequent failure, GRE-lined carbon steel provides long-lasting protection, resulting in huge savings in life-cycle cost. The operator implemented this technology for a successful trial of water-disposal wells. In the complete paper, the authors share the data from caliper logs run into, and the inspection of tubing pulled from, these disposal wells after 4 years in service. Tubular Corrosion in Operator Assets A growing emphasis on water disposal was inevitable because so much water was being produced with increased water cut and production. ADNOC Onshore operates almost 200 water-disposal wells. However, corrosion has been a common problem in these wells, such that a failure has been reported every 1–2 years. Use of corrosion-prone carbon steel for disposal strings has led to integrity issues and the need for expensive workover jobs that could cost between $1.5 million and $2 million per job. Fiberglass GRE Lining Since 2014, the operator has run 19 water-disposal wells with GRE-lined carbon steel strings. No failures have been reported, and inspections have been successful. Fiberglass tubular lining protects the internal surface of the tubing or casing inside the steel joint. Cement is pumped into the annulus between the GRE-liner outer diameter (OD) and the steel‑pipe inner diameter (ID). The final product is a completely corrosion-protected string, even under the connection area, where accessories called flares and corrosion barrier rings (CBRs) are installed (Fig. 1). The mechanical capability of the system is maintained by the steel pipe, while the internal fiberglass liner provides reliable corrosion resistance. Fiberglass Liner. The fiberglass liner shows excellent resistance in corrosive environments. As per tested and as per the manufacturer’s data sheets, the fiberglass lining system can be used in temperatures of up to 145°C, depending on hydrogen sulfide and CO2 levels in the flowing fluid. Besides being corrosion‑resistant, fiberglass lining improves the flow rate of the flowing water or oil because of the superior surface-energy properties and manufacturing quality of the liner material. The thickness of the liner varies according to the tubing size (diameter). Cement. The cement transfer applies pressure directly to the steel pipe. The cement does not bond the fiberglass liner to the steel and allows relative micromovement between the fiberglass liner and the steel pipe resulting from the difference in the thermal expansion coefficient of these two materials. Being alkaline, the cement tends to neutralize the possible presence of acid gases migrating in the fiberglass‑steel annulus; this further reduces the possibility of carbon-steel-pipe corrosion.

Injection Pultrusion of Glass-Reinforced Epoxy: Cure Kinetics, Rheology, and Force Analysis.

Pultrusion is a highly efficient continuous process to manufacture advanced fiber-reinforced composites. The injection pultrusion variant permits a higher control of the resin flow, enabling the manufacturing of a high reinforcement volume fraction. Moreover, it reduces the emission of volatile compounds that are dangerous for the operators and for the working environment. The present study proposes an experimental analysis of injection pultrusion in three different operative conditions. In particular, the activity focused on the effects of the temperature setup on the thermochemical and rheological behaviors of the resin system and on the interaction between the processed materials and the pultrusion die wall. The setup of the parameters was selected to evidence the behavior of the viscous interaction during the thermoset transition to the solid state, which is particularly challenging due to the localization of high adhesive forces related to the sharp increase in resin viscosity. Microscope observations of the cross-sections were performed to discuss the effects of the process parameters.

Experimental Analysis of the Influence of Carrier Layer Material on the Performance of the Control System of a Cantilever-Type Piezoelectric Actuator.

The subject of this article is an experimental analysis of the control system of a composite-based piezoelectric actuator and an aluminum-based piezoelectric actuator. Analysis was performed for both the unimorph and bimorph structures. To carry out laboratory research, two piezoelectric actuators with a cantilever sandwich beam structure were manufactured. In the first beam, the carrier layer was made of glass-reinforced epoxy composite (FR4), and in the second beam, it was made of 1050 aluminum. A linear mathematical model of both actuators was also developed. A modification of the method of selecting weights in the LQR control algorithm for a cantilever-type piezoelectric actuator was proposed. The weights in the R matrix for the actuator containing a carrier layer made of stiffer material should be smaller than those for the actuator containing a carrier layer made of less stiff material. Additionally, regardless of the carrier layer material, in the case of a bimorph, the weight in the R matrix that corresponds to the control voltage of the compressing MFC patch should be smaller than the weight corresponding to the control voltage of the stretching MFC patch.

Static and Fatigue Characterization of Large Composite T-Bolt Connections in Marine Hygrothermal Environments

Fiber-reinforced polymer composites have been highlighted as ideal candidates for structural applications in marine renewable energy devices, such as tidal turbines and wave energy converters. It is well understood that harsh marine environments can cause strength degradation of composite laminates, which has been extensively researched at the coupon scale; however, no research has investigated how this translates into larger-scale composite structures. This paper presents a subcomponent-scale study which investigates the effects of hygrothermal aging and subsequent static and fatigue characterization of thick composite T-bolt connections as part of a large, multilaboratory materials research effort. Of the glass-reinforced epoxy and vinylester-epoxy matrix composites tested, both showed measurable static strength degradation (4–36%) after being hygrothermally aged, even though the composite specimens were only partially saturated with water. Under tension–tension fatigue loading, the epoxy specimens performed very well in their dry states but exhibited significant degradation after hygrothermal aging. In comparison, the vinylester-epoxy specimens had much shorter fatigue lives in their dry states but exhibited no degradation after hygrothermal aging. Overall, this research demonstrates that hygrothermal aging can have significant effects on the ultimate strengths and fatigue lives of even partially saturated thick composite T-bolt connections, indicating that degradation of the outer plies on thick composite laminates can have pronounced effects on the whole structure. It discusses the challenges of building an understanding of the effects of harsh marine environments in large-scale composite structures.

Investigation of methane and ethane diffusivity in the glass reinforced epoxy composite: Experimental and simulation

New polymeric pipes have been used to overcome difficulties created by metal pipes in gas transmission lines such as corrosion and leakage. In this work, diffusion and solubility cells are designed to determine the diffusivity and possible leakage of methane and ethane gases in the glass-reinforced epoxy (GRE) composite. A composite sample with a diameter of 5.95 mm and thickness of 1.40 mm to determine the diffusivity and a composite powder to estimate the gas solubility are used. The experiments are done under temperatures varied from 25 to 40 ℃ and a pressure of 20 bar. The results show that the diffusivity of both gases increases with increasing temperature; while gas solubility decreases. The highest diffusion coefficient of methane and ethane are observed at 8.23 × 10−11 and 7.94 × 10−11 m2/s at 40 ℃, respectively. Moreover, novel correlations for estimating gas diffusion coefficient and mass flow rate in terms of temperature are developed based on the experimental data with the correlation coefficients (R2) of 0.98 and 1 and the average relative error percent (AREP) less than 4.5% and 0.5%, respectively. Interestingly, CFD (Computational fluid dynamics) results show a good consistency with experimental data for gas concentration profiles through the composite with AREP ranges of 1.95–15.78%.

Next Generation High Powered RF and Optical Packages

RF signals are radio waves that are very crucial for telecommunications. Quality communications require reliable materials which are appropriately processed to house high-powered semiconductors such as GaN and GaAs. It is equally crucial to accommodate passive electronic components along with these semiconductors into the housings for the Next Generation RF package or GenPack™. Evolving semiconductor technologies demand fail-safe packages to protect the devices in all applications and environmental conditions. Future aircraft, EV cars, spacecraft, augmented and/ or virtual reality headsets, medical devices and many more technologies require operating at a higher power and frequency with a proper thermal and power management platform. The higher speeds of telecommunications hinge on the performance of semiconductors and their packages. Therefore, the GenPack™ and packaging process are becoming crucial pieces of the supply chain. Rugged GenPack™ RF packages differ in several ways compared to the traditional air cavity packages. For instance, FR-4 or Flame-Retardant glass-reinforced epoxy laminate material can be replaced with Aluminum Nitride or Alumina Oxide, Silicon Nitride or even Sapphire. The switch offers mechanical bonding directly onto the thermal spreader. Traditional circuits created on printed circuit boards have limited ability to dissipate heat due to the low thermal conductivity of FR4. Circuits created on ceramic can dissipate higher amounts of heat. As in the organic FR4 boards, multiple vias can be formed in the ceramic substrates to create metal pads top the ceramic that are grounded to the flange beneath the ceramic. A metal flange can be positioned beneath the ceramic to provide a heat spreader and electrical ground that can be bolted onto a heatsink. Flanges can be made from a diamond metal matrix composite instead of lower thermal conductivity materials to provide much more efficient thermal transfer. Furthermore, narrow leads offer optimized impedance at RF and microwave frequencies. A range of ceramic and flange materials can be selected to optimize GenPack™ RF Packages with cost, quality, and performance in considerations for the respective applications.

Miniaturized and high gain circularly slotted 4×4 MIMO antenna with diversity performance analysis for 5G/Wi-Fi/WLAN wireless communication applications

A miniaturized with a high gain four port Multiple-Input Multiple-Output (MIMO) is presented in the manuscript. The presented design contains four radiating patch elements with a Defected Ground Structure (DGS). The shape of the radiating element is identified after the analysis of three stages. The design optimization is performed by changing the diameter of the circle loaded in the patch region and changing the length of the ground layer. The design is investigated for L, S, C, and X frequency band regions. The structure is designed using flame-retardant glass-reinforced epoxy laminate material (FR4) substrate material. The physical size of the four-port structure is 78x50 mm2. Three resonating frequency bands are observed at 2.02 GHz, 5.87 GHz and 11.19 GHz. The structure provides minimum return loss of −10.27 dB, −18.51 dB and −18.59 dB. The proposed design achieves a peak bandwidth of 3.94 GHz, and a maximum gain of 10.03 dBi, Various diversity parameters, including Total active reflection coefficient (TARC), Envelope Correlation Coefficient (ECC), mean effective gain (MEG), Diversity Gain (DG), and channel capacity loss (CCL), have been thoroughly analyzed. The measured and simulated outcomes are compared and analyzed. All performance indicators meet the allowed limits, demonstrating the suitability of the design for 5G, Wi-Fi and WLAN wireless communication applications.

Influence of interphase characteristics on the elastic modulus of unidirectional glass-reinforced epoxy composites: a computational micromechanics study

Abstract This article briefly discusses the role of interphase in the elastic moduli of unidirectional fiber-reinforced polymer composite materials. For this unidirectional glass fiber was chosen as reinforcement, and epoxy was selected as the matrix. A hexagonally packed representative volume element is used for the micromechanical analysis. Experimental validation was initially used to verify the accuracy of the established equations of the rule of mixing, Composite Cylinder Assemblage, Chamis, Halpin and Tsai, and Puck. The Chamis equation was found to be the most reasonable. Then the finite element approach in which interphase has been included was used to estimate the elastic moduli. The finite element model without interphase and the experimental result were taken as a reference. The influence of interface ratio and property of interphase on the homogenised elastic properties of the unidirectional fiber-reinforced polymer composites is analysed. A micromechanics plugin in Abaqus software was used to estimate the density and Young’s modulus of the unidirectional fiber-reinforced polymer composites. The interphase properties are varied, having 6.25%, 12.5%, 25% and 50% influence of the fiber phase and the remaining influence of the matrix phase with interface ratios of 0.1, 0.2 and 0.3. The interface ratio of 0.3, having 6.25% fiber phase influence, gave the most reasonable moduli values (with an error <10%) compared to the mean experimental moduli. The study showed interface ratio and interphase properties to critically influence the overall elastic property of the unidirectional fiber-reinforced polymer composites.

Experimental Analysis of Hysteresis in the Motion of a Two-Input Piezoelectric Bimorph Actuator

This article presents a comparison of hysteresis courses in the motion of a two-input actuator (bimorph) and hysteresis in the motion of a single-input actuator (unimorph). The comparison was based on the results of laboratory and numerical experiments, the subject of which was an actuator built of three layers: a carrier layer from a glass-reinforced epoxy laminate and two piezoelectric layers from Macro Fiber Composite. The layers were glued together, and electrodes in the Macro Fiber Composite layers were connected to a system that included an analogue/digital board and a voltage amplifier. The main purpose of this research was to compare the characteristic points of the hysteresis curves of the displacement of the bimorph actuator with the characteristic points of the hysteresis curves of the unimorph actuator. Based on the research results, it was noticed that, in the bimorph, the maximum hysteresis and mean hysteresis values increase faster than the maximum displacement of a beam tip. However, values of characteristic input voltages for hysteresis loops—voltage corresponding to a maximum displacement of the actuator beam tip and voltage corresponding to maximum hysteresis—are almost the same for the bimorph and unimorph. From a practical point of view, it was noticed that the unimorph is a better choice compared to the bimorph in applications in which high changes in frequencies of input voltages appear.

A Modified-square Slot Antenna with Circular Polarization Characteristics for Military Band Applications

In this work, the design and performance of a circularly polarized (CP) antenna designed using characteristic modal analysis (CMA) for military band application is presented. The substrate used is single-sided glass-reinforced epoxy and the antenna dimensions are 37×37×1.6 mm 3 . The antenna is compact, low-profile, circular polarized having an ARBW of around 500 MHz (center frequency 4.6 GHz). A coplanar waveguide (CPW) fed monopole antenna is used for excitation of the modified-square slot antenna that incorporates quarter section of circular symmetrical patches on the four corners. A stub orthogonal to the CPW fed monopole capacitively tunes the low Q mode as identified by CMA technique to shift to a lower frequency to create degenerate modes in military band for circular polarization generation. The 3-dB AR bandwidth of the antenna is in the frequency range 4.43- 4.9 GHz and measured value of impedance bandwidth is 3.33 GHz. The fractional ARBW and impedance BW are 10.07 % and 61.6 % respectively. The peak antenna gain in the CP frequency band is 3.75 dBic. The proposed antenna exhibits good polarization purity, the minimum axial ratio is 1.38 at 4.6 GHz. The broad circular polarized antenna is suited for military applications covering the frequency range 4.43-4.9 GHz.

Graphene-Enhanced Screen-Printed BiFeO3-Based Thermistors

In this study, serigraphic-grade BiFeO3-based ink formulations are produced and then mixed with graphene to enhance the performances of screen-printed thermistor devices. The devices are printed atop a standard thermally boosted glass-reinforced epoxy (FR-4) substrate coated with interdigitated gold electrodes. The broader operating temperature range of these thermistors makes them compatible with standard printed circuit board (PCB) manufacturing and operating conditions. Thus, we achieve highly sensitive devices with a temperature coefficient of resistance (TCR) of −0.96%/°C, which is the highest sensitivity reported yet for any graphene-based thermistor operating from 25 to 170 °C. The best-performing devices are loaded with 3.5 wt % graphene. These low-hysteresis and stable thermistors boast a thermal index (β-coefficient) of 864 K. This optimal graphene loading occurs just above the percolation threshold.

Quasi-static axial crushing performance of thin-walled tubes with circular hole discontinuities

This paper investigates the crashworthiness performance of square pipes with induced holes. Glass reinforced epoxy (GFRP) specimens were fabricated and tested under quasi-static axial crashing. Four design parameters were chosen, each at three levels, to calculate crashworthiness indicators. The design parameters are the hole diameter (d), the hole position to specimen length ratio (P/L), the number of holes and distribution (n), and crosshead speed (V). Taguchi technique has been adapted to get the optimum crashworthiness parameters. Experiments based on Taguchi’s orthogonal array with 9 experimental runs (L9) were performed. Optimal conditions with the maximum absorbed energy (U) and minimum initial peak force ([Formula: see text]) were determined. The main effects, signal to noise ratio (S/N), and analysis of variance (ANOVA) have been investigated. Results indicated that “V” followed by “d” are the highest influencing parameters on the values of “U” with a contribution of 49% and 43%, respectively. The dominant influencing parameter on the values of [Formula: see text] is “n” with a contribution of 94%. Finally, confirmation tests were carried out to validate the estimated model with respect to experimental results. The optimum U and [Formula: see text] of GFRP square pipes with circular cutouts were compared with those of non-porous specimens.

Interaction of Geopolymer Filler and Alkali Molarity Concentration towards the Fire Properties of Glass-Reinforced Epoxy Composites Fabricated Using Filament Winding Technique.

This paper aims to find out the effect of different weight percentages of geopolymer filler in glass-reinforced epoxy pipe, and which can achieve the best mechanical properties and adhesion between high calcium pozzolanic-based geopolymer matrices. Different weight percentages and molarities of epoxy hardener resin and high calcium pozzolanic-based geopolymer were injected into the glass fiber. By manually winding filaments, composite samples were produced, and they were then allowed to cure at room temperature. To determine how well the geopolymer matrices adhere to the fiber reinforcement, the microstructure of the composites’ surfaces and perpendicular sections were examined. Maximum values of compressive strength and compressive modulus were 94.64 MPa and 2373.58 MPa, respectively, for the sample with a weight percentage of filler loading of 30 wt% for an alkali concentration of 12 M. This is a relatively wide range of geopolymer weight percentage of filler loading from 10 wt% to 40 wt%, at which we can obtain high compressive properties. By referring to microstructural analysis, adhesion, and interaction of the geopolymer matrix to glass fiber, it shows that the filler is well-dispersed and embedded at the fiber glass, and it was difficult to determine the differences within the range of optimal geopolymer filler content. By determining the optimum weight percent of 30 wt% of geopolymer filler and microstructural analysis, the maximum parameter has been achieved via analysis of high calcium pozzolanic-based geopolymer filler. Fire or elevated temperature represents one of the extreme ambient conditions that any structure may be exposed to during its service life. The heat resistance or thermal analysis between glass-reinforced epoxy (GRE) pipe and glass-reinforced epoxy pipe filled with high calcium pozzolanic-based geopolymer filler was studied by investigating burning tests on the samples, which shows that the addition of high calcium pozzolanic-based geopolymer filler results in a significant reduction of the melted epoxy.

In-lab simulation of CAD/CAM grinding and intaglio surface treatments of 4YSZ monolithic restorations: Effect on its load-bearing capacity under fatigue

ObjectivesTo evaluate the effect of in-lab simulation of CAD/CAM grinding and intaglio surface treatments on the surface characteristics (topography and roughness) and fatigue behavior of adhesively luted 4YSZ simplified restorations. MethodsCeramic discs (Ø = 10 mm, thickness = 1 mm) were randomly allocated into 6 groups considering: “In-lab simulation of CAD/CAM grinding” (ground or polished) and “intaglio surface treatments”: Ctrl (without surface treatment), AlOx (aluminum oxide air abrasion) or GLZ (glaze spray application). The surface roughness of all samples was measured, the treated discs received a ceramic primer, were luted with resin cement onto a dentin analogue material (woven glass-reinforced epoxy resin) and tested under a cyclic fatigue test (step-stress approach, n = 15; 1.4 Hz, 10,000 cycles/step, step-size of 100N starting at 200N until failure). A complementary analysis was performed to corroborate the findings in the fatigue test that the glaze fill defects increase the mechanical properties of the ceramic. To do so, bars (n= 10; 1.0 × 1.0 × 12 mm; considering the groups: N-ID: non-indented; ID: indented; ID-GLZ: indented plus glaze spray application) were indented in a vickers hardness tester to produce a crack pattern, treated with glaze or not, and then submitted to flexural strength tests (FS). Fractographic and topographic analysis were performed. ResultsIn-lab simulation of CAD/CAM grinding decreased the fatigue failure load of the 4YSZ ceramic when comparing polished and ground groups, regardless of surface treatment. GLZ induced better fatigue performance compared to the air abrasion, regardless of the grinding condition (ground or polished surface). The results of the flexural strength test corroborated the findings in the fatigue test, as the ID-GLZ group presented superior FS than the ID group, however both had inferior FS than N-ID. There is an inverse association between roughness and fatigue failure load, as the higher the surface roughness, the lower the fatigue failure load. Failures in the fatigue and flexural strength tests started from the face subjected to tensile stresses. ConclusionIn-lab simulation of CAD/CAM grinding had a detrimental effect on the fatigue behavior of 4YSZ and glaze spray induced better 4YSZ performance compared to the air abrasion. The intaglio surface treatments differently influenced the 4YSZ fatigue performance, however, only glaze spray can reverse the damage caused by the grinding.

USE OF GLASS REINFORCED EPOXY PIPE IN PLACE OF CARBON STEEL PIPE IN NIGER DELTA.

This research work uses gravimetric analysis for corrosion tests performed to determine the weight loss and corrosion extent on carbon steel and glass reinforced epoxy (GRE) specimens. Comparative results for both specimens are analysed to justify the use of glass reinforced epoxy pipe as an effective control measure for the corrosion of oil pipelines used for the transportation of hydrocarbon products. The values obtained from the experiment are used to develop regression model which can be helpful to predict the corrosion extents on both materials within the test composition. Coefficient of determination is explored to ascertain the reliability of the regression models. The results obtained indicated that 99 percent of the original uncertainty has been explained by the regression models. From the experimental results, glass reinforced epoxy test specimens had better resistant to corrosion than carbon steel test specimens which makes it attractive alternative to the conventional carbon steel pipe for the transportation of hydrocarbon products in the Niger Delta of Nigeria. Keywords: Carbon steel, Corrosion extent, Gravimetric analysis, GRE, Regression models.

Damage self-sensing and strain monitoring of glass-reinforced epoxy composite impregnated with graphene nanoplatelet and multiwalled carbon nanotubes

Abstract The damage self-sensing and strain monitoring of glass-reinforced epoxy composites impregnated with graphene nanoplatelets (GNPs) and multiwalled carbon nanotubes (MWCNTs) were investigated. Hand lay-up and vacuum bagging methods were used to fabricate the composite. Mechanical stirrer, high shear mixer, and ultrasonic probe were used to mix the nanofiller and epoxy. The loadings of the nanofiller used were 0.5, 1.5, 3, and 5 wt%. The specimens were tested using in situ electromechanical measurements under mechanical tests. The results show that the type and weight content of the nanofiller affect the electrical properties, damage self-sensing behaviour, and mechanical properties of the composites. The electrical conductivity of the GNP-glass and MWCNT-glass composites increased with nanofiller content. The tensile and flexural strengths of the composite improved with the addition of GNP and MWCNT nanofillers from 0.5 to 3 wt%. The 3 wt% nanofiller loading for GNP and MWCNT produces better mechanical–electrical performance. Field emission scanning electron microscopy revealed the dispersion of GNP and MWCNT nanofillers in the composites.

Nanostructured AlTiSiN/CrVN/ZrN coatings synthesized by cathodic arc deposition- mechanical properties and cutting performance

Multicomponent and multilayer coatings have been attracting significant research interest, and these coatings allow the deposition of graded layers with a continuous variation of the concentration of the components to fulfill specific requirements at the substrate interface or that at the surface. On the basis of the binary compounds TiN, CrN and ZrN, various deposition strategies were developed to improve or adapt the hard coatings to a specific tribological problem. In this study, a cathodic arc deposition technology was used to deposit the AlTiSi/CrV/Zr and multilayer nitride coatings of AlTiSiN/CrVN/ZrN. By controlling the rotation speed of the substrate, hierarchical gradient and multilayered structures containing periodic AlTiSiN, CrVN and ZrN layers were found in the multilayer nitride coatings. Microstructure, mechanical properties and cutting applications were discussed. The highest hardness was obtained for the multilayered AlTiSiN/CrVN/ZrN coating with modulation period of 13.5 nm. The presence of multicomponent AlTiSiN/CrVN/ZrN with nanolayer structure mainly attributed to the formation of strong metal‑nitrogen bonding enhanced the hardness of the coatings. For the field test of cutting, a glass-reinforced epoxy laminate material was machined by the coated WC-Co end mills using a milling machine at high cutting spindle rotational speed of 40,000 rpm. The obtained results showed that the periodic thickness of the multilayer structure had a direct effect on the mechanical properties and cutting performance of the coatings. The design of nanostructured AlTiSiN/CrVN/ZrN hard coatings improved the overall tribological performance and showed applicability of these coatings in high speed cutting of glass-reinforced epoxy laminate materials.