Universal Tensile Testing Machine Research Articles

Effect of Al on characterization and properties of AlxCoCrFeNi high entropy alloy prepared via electro-deoxidization of the metal oxides and vacuum hot pressing sintering process

AlxCoCrFeNi high-entropy alloys with different Al contents (x in molar ratio, x = 0 – 2.0) were prepared by electrochemical process using the mixed metal oxides as the precursor. The effects of Al addition on the crystal structure, microstructure, mechanical property and corrosion behavior were investigated by XRD, XPS, SEM, FE-EPMA, universal tensile testing machine, Vickers hardness tester and electrochemical workstation. With the increase of Al contents, the crystal structure of AlxCoCrFeNi HEAs transformed from FCC to the mixed crystal structures of FCC and BCC, finally, to BCC + B2. The σ-phase was formed in AlxCoCrFeNi (x = 0.8 – 1.5) HEAs during the electrolysis deoxidization. The bulk HEAs could be prepared successfully via vacuum hot pressing sintering process. The bulk HEAs exhibit excellent ultimate tensile strength (UTS) and hardness. The hardness of the Al0 (245.2 HV) HEA and Al0.3 (261.2 HV) HEA was twice high of the sample prepared by arc-melting method. Compared with 304 stainless steel (304SS) and AlxCoCrFeNi HEAs prepared by other method, AlxCoCrFeNi HEAs prepared by the united process shows a comparable corrosion resistance in acid, alkali and salt aqueous solutions.

Development of Polymeric Membranes for Oil/Water Separation.

In this work, the treatment of oily wastewater was investigated using developed cellulose acetate (CA) membranes blended with Nylon 66. Membrane characterization and permeation results in terms of oil rejection and flux were compared with a commercial CA membrane. The solution casting method was used to fabricate membranes composed of CA and Nylon 66. Scanning Electron Microscopy (SEM) analysis was done to examine the surface morphology of the membrane as well as the influence of solvent on the overall structure of the developed membranes. Mechanical and thermal properties of developed blended membranes and a commercial membrane were examined by thermogravimetric analysis (TGA) and universal (tensile) testing machine (UTM). Membrane characterizations revealed that the thermal and mechanical properties of the fabricated blended membranes better than those of the commercial membrane. Membrane fluxes and rejection of oil as a function of Nylon 66 compositions and transmembrane pressure were measured. Experimental results revealed that the synthetic membrane (composed of 2% Nylon 66 and Dimethyl Sulfoxide (DMSO) as a solvent) gave a permeate flux of 33 L/m2h and an oil rejection of around 90%, whereas the commercial membrane showed a permeate flux of 22 L/m2h and an oil rejection of 70%.

Evaluation of compression strength of intumescent char using ASTM 1162 00

Intumescent coatings employ the heat barrier effect of an expanded char in the fire protection of the underlying substrates. The effectiveness of an intumescent system is dependent on the strength and ability of the char to remain intact upon exposure to fire. Many approaches have been employed to measure the strength of the intumescent char, but there still remains the need for an established standard procedure. In the present study, the compressive strengths of reinforced and unreinforced intumescent chars are evaluated using the compression test for cellular materials (ASTM 1162 00). This standard procedure enabled easy evaluation of compressive strength by employing the principle of deformation force as a function of the axial displacement of char under an active load by using the common universal tensile testing machine. The force–deformation graph revealed an exponentially increasing curve with two distinct regions, an initial region of low force to high deformation representing the collapse of the cellular pores and a high-force–low-deformation region attributed to the bulk mass effect of the compressed char. The results showed that the force needed to compress a bauxite residue-reinforced char to 10% deformation increased by 59%, while the compression strength increased by 13.08% over the control char.

Effect of Ni and Sr additions on the microstructure, mechanical properties, and coefficient of thermal expansion of Al-23%Si alloy

In this paper, the combined and individual effect of strontium (Sr) and nickel (Ni) additions on the microstructure and mechanical properties of hypereutectic Al-23Si alloy was studied using an optical microscopy, universal tensile testing machine and Brinell hardness tester. The wear properties and coefficient of thermal expansion of the melt treated samples were determined using pin on disc wear testing machine and linear expansion measurement unit respectively. The results indicate that the Ni additions significantly enhanced the mechanical properties of the alloy, whereas, presence of Sr was detrimental. It was observed that the improvement in mechanical properties due to Ni was primarily due to refinement and transformation of the star shaped primary silicon into polyhedral crystals. However, the addition of Sr, both as separate and when combined with Ni, transformed the primary silicon into a faceted crystal and hence decreased the mechanical property. Among all, the Ni melt treated alloy samples showed lowest wear rate and coefficient of thermal expansion.

Effects of in‐situ reactive phenolic resin on shape memory performance of polynorbornene

AbstractIn this paper, resorcinol prepolymer (HT1005) in‐situ reacted with hexamethoxymethyl melamine (HMMM, formaldehyde donor) to produce cured phenolic resin to modify polynorbornene (PNB) as a shape memory polymer (SMP). A moving die rheometer (MDR) was used to characterize the crosslinking degree of phenolic resin. Fourier transform infrared spectroscopy, differential scanning calorimeter, universal electronic tensile testing machine, dynamic mechanical analysis and X‐ray diffraction was used to investigated the mechanical properties and shape memory performance of PNB composites. Infrared results showed that HT1005 reacted with HMMM forming a chemical cross‐linking network in PNB. With the increase of HT1005 and HMMM, the phenolic resin network was gradually improved. When stress was applied to the composite, the phenolic resin rigid network first beared part of the external force, which improved the mechanical properties of the composite. When the content of HT1005 was too much, its dispersibility will become poor, and the rigid phenolic resin network will be too dense, which limited the recovery of PNB molecular chains. A small amount of HT1005 will be more uniformly dispersed in the PNB, the strength of the phenolic resin network was moderate, and the composite material had excellent shape memory and mechanical properties.

Evolution in Microstructure and Mechanical Properties of Inconel 783 Alloy Bolts after Long Term High-Temperature Aging at 700 °C

This paper described systematically the changes in microstructure and mechanical properties of Inconel 783 alloy after a considerably long time (equivalently 55,000 h, about 76.4 months) of thermal exposure. Based on the Inconel 783 alloy bolts of an intermediate pressure main stop valve used in a 1000 MW ultra-supercritical unit, the evolution of microstructures and mechanical properties were studied after 700 °C aging temperature with different aging times (1000 h, 3000 h and 20,000 h, corresponding to about 1.4 months, 4.2 months and 27.8 months, respectively), using an optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffractometer (XRD), a universal tensile testing machine and impact testing machine. The results indicated that the bolts aged for 1000 h in two temperatures, showing the second needle β phase, of which the quantity and size obviously increased with aging time. Meanwhile, the characteristics in quantity and shape of the primary β phase changed obviously with the aging time, which transformed to strip the Ni5Al3 and Laves-Nb-rich brittle phase in the matrix after aging for 20,000 h. The size of the γ’ phase grew bigger with aging time, and orientation distributions have been observed obviously at 3000 h aging in 700 °C. Compared with the 650 °C aging temperature, the coarsening of γ’ precipitates and second needle β, the orientation distributions of γ’ were more obvious at the 700 °C aging temperature with aging time, which resulted in the rapid decline in yield strength and tensile strength and obvious increase in the brittleness for Inconel 783 alloy bolts.

The Microstructure, Thermal, and Mechanical Properties of Sn-3.0Ag-0.5Cu-xSb High-Temperature Lead-Free Solder

To obtain Sn-3.0Ag-0.5Cu-xSb (x = 0, 25, 28, and 31) high-temperature lead-free solder antimony was added to Sn-3.0Ag-0.5Cu solder. The microstructure, thermal properties, and mechanical behavior of the solder alloy prepared were studied by using JSM-5610LV scanning electron microscope, Germany STA409PC differential scanning calorimeter, AG-I250KN universal tensile testing machine, and other methods. The SEM-EDS results showed that after adding Sb, SnSb phase was formed in the β-Sn matrix phase. The newly formed SnSb phase and the existing Sb in the solder alloy can inhibit the generation of IMC and refine the IMC layer. The addition of Sb significantly increased the melting temperature of the solder alloy. Among them, the thermal performance of Sn-3.0Ag-0.5Cu-25Sb is the best. The melting temperature of Sn-3.0Ag-0.5Cu-25Sb is 332.91 °C and the solid–liquid line range of Sn-3.0Ag-0.5Cu-25Sb solder alloy is 313.28–342.02 °C. Its pasty range is 28.74 °C, lower than 30 °C, which is beneficial for soldering. The test results of the mechanical behavior of Sn-3.0Ag-0.5Cu-xSb solder alloy show that with the increase of Sb addition, the ultimate tensile strength of the solder alloy also increases. However, the change of the elongation of the solder alloy is the opposite. The ultimate tensile strength of the solder alloy increased from 29.45 MPa of Sn-3.0Ag-0.5Cu solder to 70.81 MPa of Sn-3.0Ag-0.5Cu-31Sb solder. The reason for the increase in the strength of the solder alloy is the reduction of the thickness of IMC and the solid solution hardening effect of Sb.

Comparison between two coating techniques of glass fiber posts treated with hydrogen peroxide 35% on its stability in root canals after cementing using resin cement (In vitro comparative study)

Aim of the Study: This research aims to compare two techniques of coating glass fiber posts to define the best technique that achieves the higher tensile resistance after cementing with dual-cure resin cement into prepared human teeth root canals. Materials and Methods: The sample of this research consisted of 20 extracted human lower premolars which their crowns were cut horizontally 2 mm above the cementoenamel junction, then the root canals were treated endodontically with suitable instruments and divided into 2 groups according to techniques used in coating the glass fiber posts luted into them: Group A: 10 fiber posts were coated with silane before cementing. Group B: 10 fiber posts were coated with unfilled resin before cementing. Each specimen was secured in a universal tensile-test machine. An increasing tensile force was applied on the free part of the fiber post vertically at a crosshead speed of 1 mm/min along with the long axis of the tooth until adhesive failure occurred. Results: The results of the tensile test indicated that there is no statistically significant differences in the average tensile resistance between A and B groups. Conclusions: There was no significant difference in stability strength between the technique of using silane and the technique of using unfilled resin to coat the glass fiber post before cementing with resin cement.

The effect of offset preheating on the mechanical properties of FSW aluminium alloy joint using GTA

This study aims to minimize the issue linked with the advancing side of conventional FSW AA5052 joints with the aid of gas tungsten arc preheating with 4 mm offset from the center of the weld. A universal tensile testing machine, matsuzawa hardness tester, digital optical microscope and scanning electron microscope were employed in this study to characterize the joint properties. The results reveal that the improved and uniform material flow was noticed in advancing side and the increased tensile strength about 18.1% also accounted. Moreover, the GTA preheating deeply influences the NZ microstructure by dynamic recrystallization and hardness measured in advancing side was improved significantly. Furthermore the fine dimples and extensive plastic deformation were noticed in the fracture surface which attributes to improve the joint properties.

Case study of failed feed water pump shaft in HRSG of 9F gas turbine generator unit

The failure of feed water pump shaft failure uesed in HRSG (heat recovery steam generator) of 9F class gas turbine generator unit has been systematically investigated in terms of visual inspection, fractographic, chemical component, micro structure and mechanical properties analysis using optical microscope (OM), scanning electron microscope (SEM) equipped with energy-dispersive X-ray (EDX) analysis, transmission electron microscope (TEM), elemental analyzer and universal tensile testing machine, respectively. Results suggest that the failure of feed water pump shaft was typical multiple-origin fatigue fracture resulting from torsion stress, owing to the lower mechanical properties caused by the less alloying element and alloy strengthening phase (ε-Cu, η-Ni). A detailed analysis of the micro structure revealed the existence of severe microsegregation and coarse M23C6 carbide at the grain boundaries, which accelerated the nucleation of micro holes and led to the formation of microcracks at the junction of micro holes. This failure analysis can help identification of root cause and its elimination with corrective measures undertaken.

Preparation of spherical cobalt hydroxystannate and its flame retardant and smoke suppressant effect in poly(vinyl chloride)

Spherical cobalt hydroxystannate was prepared and characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analyzer–Fourier-transform infrared spectroscopy. Results showed that cobalt hydroxystannate spheres have an average particle size of 440 nm and disperse uniformly. The flame-retardant flexible poly(vinyl chloride) treated with cobalt hydroxystannate was studied by the limiting oxygen index, universal tensile testing machine, thermogravimetric analyzer–Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and laser Raman spectra methods. Compared with the pure poly(vinyl chloride), the limiting oxygen index value of the poly(vinyl chloride) sample (PVC/10) treated with 10 phr of cobalt hydroxystannate is increased by 4% points, and its total heat release and total smoke production decreased by 18% and 50%, respectively. The result could be attributed to the water produced by the dehydration of cobalt hydroxystannate, and the interaction of cobalt hydroxystannate and the poly(vinyl chloride) matrix, which produces dense and highly graphitized char residue containing hexagonal phase graphite, CoCl2, Co2O3, and Co3O4.

Investigation of a Novel Chiral S‐Shaped Auxetic Structure under Large Tensile Deformation

The behavior of the chiral S‐shaped structure subjected to large tensile loads in both X and Y directions is reported herein. The physical samples of stainless steel 316L are fabricated by the selective laser melting technique and experimental tests are conducted on a universal tensile testing machine. The results of tensile tests in the form of deformation patterns, tensile stress–strain curves, and Poisson's ratios are shown pictorially and graphically. The orientation of the S‐shaped structure with X‐direction loading is found to exhibit higher auxeticity over the large range of tensile loading. Nonetheless, the structure is also found auxetic when loaded from Y‐direction albeit the values of negative Poisson's ratios are not as high as of the X‐directional loading.

Tunable Young's Moduli of Soft Composites Fabricated from Magnetorheological Materials Containing Microsized Iron Particles.

This study experimentally investigates the field-dependent Young’s moduli of soft composites, which are fabricated from two different magnetic-responsive materials; magnetorheological elastomer (MRE) and magnetorheological fluid (MRF). Four factors are selected as the main factors affecting Young’s modulus of soft composites: the amount of MRF, the channel pattern, shore hardness and carbonyl iron particle (CIP) concentration of the MRE layer. Five specimens are manufactured to meet the investigation of four factors. Prior to testing, the scanning electron microscopy (SEM) image is taken to check the uniform dispersion of the carbonyl iron particle (CIP) concentration of the MRE layer, and a magnetic circuit is constructed to generate the effective magnetic field to the specimen fixed at the universal tensile test machine. The force–displacement curve is directly measured from the machine and converted to the stress–strain relationship. Thereafter, the Young’s modulus is determined from this curve by performing linear regression analysis with respect to the considered factors. The tunability of the Young’s moduli of the specimens is calculated based on the experimental results in terms of two performance indicators: the relative percentage difference of Young’s modulus according to the magnetic field, and the normalized index independent of the zero-field modulus. In the case of the relative percentage difference, the specimens without MRF are the smallest, and the ones with the highest CIP concentration are the largest. As a result of comparing the normalized index of each factor, the change in shore hardness and channel pattern have little effect on the tunability of Young’s moduli, and the amount of MRF injected and CIP concentration of MRE have a large effect. The results of this study are expected to provide basic guidelines for fabricating soft composites whose field-dependent Young’s moduli can be tuned by several factors with different effects.

Microstructure and mechanical properties of maraging 18Ni-300 steel obtained by powder bed based selective laser melting process

PurposeThe purpose of this paper is to maraging 18Ni-300 steel fabricate by powder bed based selective laser melting (SLM) process. Microstructure and mechanical properties of the maraging steel part before and after heat treatment at a slow cooling rate were investigated.Design/methodology/approachThe microstructure of the printed part was observed by optical microscopy and scanning electron microscopy. The phases were determined by X-ray diffraction. The surface roughness of the part was recorded by a profilometer. The tensile properties and microhardness of the parts before and after heat treatment were characterized by an electronic universal tensile testing machine and a Vickers hardness tester, respectively.FindingsMaraging 18Ni-300 steel part comprised of the martensitic phase and a small fraction of austenite phase. After heat treatment, the volume fraction of austenite slightly increased. The surface roughness of the part was about 96 µm. The printed part was dense, but irregular pores were present. The yield strength, ultimate tensile strength (UTS), elongation and Young’s modulus of as-fabricated parts were 554.7 MPa, 1173.1 MPa, 10.9% and 128.9 GPa, respectively. The yield strength, UTS, elongation and Young’s modulus of as-treated parts were 2065 MPa, 2225 MPa, 4.2% and 142.5 GPa, respectively. The microhardness values of surface and cross-section of the as-fabricated part were 407.1 HV and 443.0 HV, respectively. After short-time heat treatment, the microhardness values of the surface and cross-section of the part were 542.7 HV and 567.3 HV, respectively. After long-time heat treatment, the microhardness values of the surface and cross-section of the part were 524.4 HV and 454.8 HV, respectively. The microhardness and tensile strength increased significantly with decreasing elongation due to the changes in phases and microstructure of the parts after heat treatment.Originality/valueThis work studied the effect of heat treatment at 550°C combined with a subsequent slow cooling rate on microstructure and mechanical properties of maraging 18Ni-300 steel obtained by the powder bed based SLM process.

Swelling behavior and mechanical properties of Chitosan-Poly(N-vinyl-pyrrolidone) hydrogels

Abstract In this research, three modified chitosan-based hydrogels are synthesized, i.e., a crosslinked chitosan hydrogel and semi- and fully-interpenetrating polymer network (IPN) chitosan hydrogels fabricated using poly(N-vinyl-pyrrolidone). A non-modified chitosan hydrogel was also synthesized as a control. These samples were compared regarding their swelling behavior and mechanical properties. The hydrogels were characterized by Fourier Transform Infrared (FTIR) analysis and microscopy observations. The effect of crosslinking on the swelling capacity and on the swelling kinetics were evaluated in distilled water, simulated gastric fluid (SGF), and simulated intestinal fluid (SIF) at 37 °C, and the data were interpreted using various kinetic models. Finally, the mechanical properties were evaluated based on the tensile strength using a universal tensile testing machine. The results revealed that the swelling process conformed to the Schott model (pseudo-second-order kinetics), with Fickian diffusion as the diffusion mechanism type. The hydrogels all showed similar trends in their swelling kinetics. However, the full-IPN hydrogel exhibited the lowest equilibrium swelling capacity and the highest swelling rate. The mechanical test results indicate that the crosslinking model affects the resulting tensile strength.

Development of a multi-functional acrylic urethane coating with high hardness and low surface energy

This study developed multi-functional acrylic urethane coating materials with anti-graffiti, anti-contamination, and anti-adhesion properties. The newly-developed coating was synthesized by high glass transition temperature (Tg) acrylic polyol and low-viscosity single-end-type silicone oil. The coating materials were chemically bonded and reacted with isocyanate to form acrylic urethane. The hardness, surface energy, color difference value, and anti-adhesion properties were examined using nanoindentation, a contact angle analyzer, a color difference meter, and a universal tensile test machine, respectively. In addition, the degradation of the coating was evaluated using an accelerated weathering test, taking into account various degradation factors (UV, humidity, high temperature, and water). In general, the properties of the coating degraded due to the loss of silicone oil after the accelerated weathering test. However, the degradation was retarded when high Tg acrylic polyol and low-viscosity single-end-type silicone oil were chemically bonded. The newly-developed multi-functional acrylic urethane coating exhibited long-term stability against an accelerated weathering test of 120 h. The developed coating will be useful in broad applications, including harsh environments such as underground walls, heritage, facilities, and subways.

Toughening Effect of Physically Blended Polyethylene Oxide on Polyglycolic Acid

Polyglycolic acid (PGA), a linear aliphatic polyester with excellent biodegradability and biocompatibility, is widely used as a medical material. However, the inherent brittleness of this material may limit its use in many other industrial applications. This study explored the toughening effect of physically blending PGA with polyethylene oxide (PEO). Standard tensile samples of different PGA/PEO blends were prepared by a torque rheometer and a microinjection molding machine. The thermodynamic properties, mechanical properties, and microstructure of the PGA/PEO samples were investigated by differential scanning calorimetry (DSC), a universal tensile testing machine, a cantilever impact tester, and field emission scanning electron microscopy (FE-SEM). The experiment ultimately found that the addition of 15 wt% PEO greatly improved the toughness of the blended PGA/PEO. A yielding process could be observed in the tensile tests, and the elongation-at-break increased from 3.67% for pure PGA to 54.14% for PGA/PEO 85:15, which shows an increase of 1475.2%. It can be concluded that the addition of PEO is a good way to increase the PGA toughness. The mechanism of PGA toughening by PEO was further analyzed, and the increase in toughness could be attributed to the existence of a continuous PEO phase that facilitated the formation and evolution of cavities between the partially compatible PGA and PEO phases.

Effect of silver nanoparticle (AgNp) mixed with calcium carbonate on impact, hardness and tensile strength properties of aluminium 6063

Mechanical properties (impact, hardness and tensile strength) characterization of samples containing homogenous mixtures of Al 6063 matrix and varying amount of silver nanoparticles mixed with calcium carbonate at 2, 4, 6% weight fractions, respectively, produced by method of stir casting were carried out. Measurement of impact energy, hardness and tensile strength of the produced samples at 24℃ (ambient) temperature was done by Charpy impact, Brinell hardness and universal tensile testing machine in accordance to ASTM E23, E384 and E8/E8M-13M, respectively. The magnitude of impact and hardness increased evidently with increase in percentage weight fraction of the AgNPs. The refined samples were examined under an optical microscope. The fracture surfaces of the impact test samples were further examined by scanning electron microscopy. There is an increase in tensile strength, elongation and modulus of elasticity of Al-AgNP composites compared to as-cast aluminium alloy. The use of stir-casting technique influences the homogeneity and microstructure of the composites positively. It is concluded that Al-silver nanocomposites possess better qualities in hardness and strength and can replace conventional aluminium alloy in terms of performance and longer life in industrial application.

On investigations of thermal conductivity, circumferential compressive strength, and surface characterization of 3D-printed hybrid blended magnetostrictive PLA composite

In past two decades, the 3D printing of thermoplastic-based composite matrix has been widely explored for different engineering applications. But hitherto little has been reported on the preparation of polylactic acid (PLA) composite-based 3D-printed circular disc to ascertain its circumferential compressive strength, thermal conductivity, and morphological properties for possible structural engineering applications. The present investigation outlines the circumferential compressive strength, thermal conductivity, and morphological properties (Shore D hardness, surface voids using fractured surface analysis) of 3D-printed PLA composite matrix. Based upon the thermal conductivity test, it has been ascertained that sample printed on fused deposition modeling (FDM) setup with infill density of 100%, infill angle of 90°, and infill speed of 70 mm/s has shown maximum thermal conductivity (0.278 W/mK). Further it has been observed that with the increase in infill density, thermal conductivity of the sample has improved. Circumferential compressive testing has been performed on universal tensile testing machine setup (with in-house developed fixtures), and from printer setting optimization viewpoint, it has been ascertained that infill density has maximum contribution for peak and break strength. Further morphological studies (surface hardness, fractured surface analysis, and surface roughness (Ra) data) have supported the observed behavior of circumferential compressive strength and thermal conductivity of 3D-printed samples.

Mechanical behavior of polyimide filament tows under high strain rate tension

The tensile properties of polyimide (PI) filament tows were measured under quasi-static state and at high strain rates with a universal tensile testing machine and a split Hopkinson tension bar, respectively. Experimental results showed that mechanical behaviors of the tows were rather sensitive to strain rate, with failure stress and modulus increasing distinctly but the elongation at break declining as the strain rate increased. Besides, the PI filament tows exhibited a higher growth rate of fracture stress than para-aramid fiber and aramid III fiber did, and scanning electronic microscopy observation on the fracture surface indicated a ductile fracture mode. With the increase of strain rate, the axial splitting of fiber intensified. Further, strength distributions of the PI filament tows were evaluated by a single Weibull distribution function, and the curve predicted was in good accordance with the experimental data obtained.