Joining Method Research Articles

Achieving interfacial thermal expansion matching between C/C composites and metal through ultrafast high-temperature shock (UHS)

A novel surface modification and joining method utilizing ultrafast high-temperature shock (UHS) has been investigated to achieve interfacial bonding between C/C composites and TC4 alloy by using Joule heating effect. The process involves surface selective oxidation of the C/C composites and subsequent ultrafast joining, both achieved within short time periods of 30 s and 20 s, respectively. Surface selective oxidation created annular gaps on the C/C composite surface which increased the contact area between the filler alloy and the base material, while suppressing the propagation of cracks. Joule heating of the C/C composites induced a non-equilibrium temperature field, which melted the filler alloy and facilitated interfacial joining through heat conduction. Notably, the temperature of TC4 metal (CTE ∼9.5 × 10−6 K−1) was significantly lower than that of the C/C composites (CTE ∼1.5 × 10−6 K−1), thus suppressing the expansion of TC4 near the heterointerface due to the self-limiting effect exerted by the cold end. As a result, the thermal expansion matching was improved and the residual stress in C/C-TC4 heterostructure was relieved. The shear strength of optimal joints reached 31.7 MPa, representing a 2.4 times increase compared to the conventional joining method.

Low-temperature direct diffusion bonding of Zr702 alloys via electric current assistance

Integrated zirconium (Zr) alloy fuel claddings require low-temperature and high-efficiency joining technologies for nuclear applications. However, conventional direct-joining technologies make it challenging to satisfy critical requirements at relatively low temperatures in a short time. As a promising alternative, the electric-current-assisted joining (ECAJ) method was studied to reduce the joining temperature and time required for the direct joining process. ECAJ was performed on a spark plasma sintering apparatus, with the specimens assembled with and without graphite dies in the two models. The microstructural evolution and mechanical properties of Zr/Zr joints were investigated at 600 − 900 °C for 1 s to 30 min under a pressure of 30 MPa using different configurations with or without a graphite die. While the joint quality varied with the joining conditions, no significant phase transformation, abnormal grain growth, or preferential orientation was observed at the interface. The maximum shear strength of 404 ± 78 MPa and hardness of 370.9 ± 49.8 HV were achieved at 600 °C for 10 min using a die-less configuration. The joining mechanism was discussed in terms of the potential thermal and electric effects inside the specimen, with the low-temperature joining mechanism attributed to the combined effect of transient overheating and electric-field-accelerated element self-diffusion at the interface, with the latter playing a leading role.

Genetic characterization and evaluation of pigmented maize (Zea mays L.) landraces of the North East Hill Region of India-an established centre of maize diversity

Abstract The North East Hill Region (NEHR) of India is home to diverse maize landraces including pigmented accessions rich in antioxidants and nutritional properties. The present study attempted to characterize a representative collection of this mostly unexplored diversity. Altogether eighty-three local maize landraces from the seven hill states of the NEHR were studied with special emphasis on pigmentation diversity. For the morphological traits, a significant ANOVA indicated the presence of substantial genetic variability for which selection would be fruitful. A number of these accessions were found to have traits that help cope with moisture stress, improve stalk strength and optimize photosynthesis. Principal component analysis studies for the yield attributing traits indicated that ear weight was most variable. The bleaching/histological studies confirmed that anthocyanin pigment when present was always restricted to the aleurone layer of the kernels, typical of blue maize. Quantitative analysis for kernel anthocyanin/phlobaphene content also revealed genetic differences among the accessions. Genetic analysis using the model-based STRUCTURE indicated significant population structuring among the accessions. Specifically, for the pigmentation diversity studies both principal coordinate analysis and neighbour joining methods revealed near concurrent population structuring due in part to the high differentiation of seven of the twenty-one pigmentation specific loci studied. The results obtained provide comprehensive evidence of a significant amount of genetic differentiation among the landraces under study. Landraces are valuable reservoirs of favourable alleles for which selection can be made and, as in this study, identify accessions for breeding maize with enhanced levels of beneficial secondary metabolites.

Bonding of ceramics to silver-coated titanium-A combined theoretical and experimental study.

It would be very beneficial to have a method for joining of ceramics to titanium reliably. Although several techniques have been developed and tested to prevent extensive interfacial chemical reactions in titanium-ceramic systems, the main problem of the inherent brittleness of interfaces was still unsolved. To overcome this problem also in dental applications, we decided to make use of an interlayer material that needs to meet the following requirements: First, it has to be biocompatible, second, it should not melt below the bonding temperatures, and third, it should not react too strongly with titanium, so that its plasticity will be maintained. Considering possible material options only the metals: gold, platinum, palladium, and silver, fulfill the first and second requirements. To find out-without an extensive experimental testing program-which of the four metals fulfills the third requirement best, the combined thermodynamic and reaction kinetic modeling was employed to evaluate how many and how thick reaction layers are formed between the interlayer metals and titanium. With the help of theoretical modeling, it was shown that silver fulfills the last requirement best. However, before starting to test experimentally the effect of the silver layer on the mechanical integrity of dental ceramic/Ag/Ti joints it was decided to make use of mechanical analysis of the three-point bending test, the result of which indicated that the silver layer increases significantly the bond strength of the joints. This result encouraged us to develop a new technique for plating silver on titanium. Subsequently, we executed numerous three-point bending tests, which demonstrated that silver-plated titanium-ceramic joints are much stronger than conventional titanium-ceramic joints. Hence, it can be concluded that the combined thermodynamic, reaction kinetic, and mechanical modeling method can also be a very valuable tool in medical research and development work.

Effect of Friction Pressure on the Mechanical Properties of CDFW Dissimilar Aluminium 6061-T6 and Stainless steel 304 Welding Joints

Welding technology has significantly developed in the industrial sector along with advances in manufacturing technology. The demand for joining methods combining dissimilar metals is increasing in the industrial sector. However, joining dissimilar metals is challenging because of differences in physical and mechanical properties. Continuous drive friction welding is a solid-state joining method widely used to join dissimilar metals. The research aimed to determine the effect of variations in friction pressure on the mechanical properties of continuous drive friction welding joints with dissimilar materials, Aluminum 6061 T6 and Stainless Steel 304. The process parameters used in this welding were the friction pressures used were 30 MPa, 35 MPa, and 45 MPa. The friction time is 2 seconds, the rotation speed is 1000 rpm, and the upset pressure is 50 MPa. Then, welded joints were evaluated for Vickers microhardness and microstructure observations. Based on the research results, it shows that the temperature distribution and microstructure results show that there is a change in the hardness value of the aluminum material. In contrast, the 304 stainless steel material experiences an insignificant change in the hardness value.

Influence of Metal Surface Structures on Composite Formation during Polymer–Metal Joining Based on Reactive Al/Ni Multilayer Foil

Progressive developments in the field of lightweight construction and engineering demand continuous substitution of metals with suitable polymers. However, the combination of dissimilar materials results in a multitude of challenges based on different chemical and physical material properties. Reactive multilayer systems offer a promising joining method for flexible and low‐distortion joining of dissimilar joining partners with an energy source introduced directly into the joining zone. Within this publication, hybrid lap joints between semicrystalline polyamide 6 and surface‐structured austenitic steel X5CrNi18–10 (EN 1.4301) are joined using reactive Al/Ni multilayer foils of the type Indium–NanoFoil. The main objective is to examine possibilities of influencing crack initiation in the foil plane by variation of joining pressure and different metal surface structures with regard to geometry, density, and orientation. Thus, the position of foil cracks is superimposed onto the metal structure and associated filling with molten plastic is improved. Consequently, characterization of occurring crack positions as a function of joining pressure and metal structure, analysis of the composite in terms of structural filling and joint strength, as well as possible causes of crack initiation are evaluated.

Significantly enhanced joint strength and fatigue life of aerospace composite joints by using novel PEEK/PPS woven meshes as joining agent

The development of advanced joining methods for carbon fibre/epoxy composites is critical for aerospace applications. Herein, advanced PEEK/PPS meshes were used to join carbon fibre/epoxy composites upon a novel co-curing process. The meshes were surface-activated upon an atmospheric plasma technique, which largely promoted the chemical interactions between the meshes and the composite epoxy matrix. The quasi-static joint strengths at both of 22 °C and 130 °C and fatigue loading resistance of the composite joints were evaluated using a single-lap joint test and the corresponding failure mechanisms were investigated. Encouragingly, the lap-shear strengths and fatigue resistance of the PEEK/PPS mesh-joined composites were larger than that of their counterparts bonded by an aerospace adhesive. Subsequent analysis on the failure surfaces proved PEEK/PPS fibre damage and epoxy crack were the main failure mechanisms of the PEEK/PPS co-cured joints. This work proposed a novel method for the production of robust aerospace joints by co-cure joining the composites using advanced PEEK/PPS meshes.

Direct spot joining of thin gauge aluminum alloy to stainless steel and joint performance in a corrosion environment

Direct joining of aluminum alloy and steel sheets offers a great potential for achieving effective structural lightweighting for transportation systems. The major challenge is how to avoid the formation of brittle intermetallic compounds (IMCs), which can be detrimental to joint load capacity and corrosion resistance. This paper presents a friction-based direct solid-state joining method for welding thin aluminum alloy (AA6061-T6) to stainless steel (316). Using a flat head friction heating tool, high quality interfacial bonding was achieved under a spot time of 20s and 1000 rpm without detrimental IMCs. The effects of an automotive-relevant corrosion environment condition on joint strengths were then examined through mechanical testing. The test results show that aluminum and stainless-steel spot joints produced by the proposed method exhibit no corrosion-induced damage or cracking nor any noticeable reduction in strengths, resulting in dominantly ductile failure mode.

Ageing behaviour of folded joints produced by fusion bonding of an outer metal sheet and an inner organic sheet

Adhesive hemming is a process used in the automotive industry to join two metal sheets with good structural performance and good optical appearance of the rim. A new approach is to replace the inner metal sheet by a fibre-reinforced thermoplastic polymer sheet. The joining method used is fusion bonding. This can reduce process time, cost and weight of the finished part. As process route cold hemming is used where the outer metal sheet is first folded around the inner organic sheet at room temperature and afterwards thermally joined by induction. The aim of this work in particular is to investigate the behaviour under accelerated ageing conditions. Especially the cathodic dip coating as corrosion prevention and the air in the fold were varied. The latter can vary in the production process due to manufacturing. In addition, a pre-treatment of the metal surface with a laser was investigated to enhance the mechanical strength of the joint. The samples were produced with a three-step hemming process combined with inductive heating. The applied materials were an organic sheet made of polyamide-6 as matrix material and zinc coated steel. Conditioning according to DIN 1110 and the ageing test VDA 233-102 were applied to laboratory samples. It was shown that conditioning of the specimen reduces the maximal pull out force only slightly while ageing according to VDA 233-102 decreases the pull out force by about 50 %. Furthermore, the air gap has a significant influence on the ageing behaviour of the specimen while the cathodic dip coating only prevents the steel from corrosion but has no influence on the bond strength.

Curing of epoxy adhesives between thin metal foils by means of inductive heating

Metal foils are being widely used, from the chemical or electronics sector to household appliances. The joining of these foils by adhesive bonding is often the preferred method due to discolouring and warping under the thermal stresses of other joining methods, such as welding. However, long curing times are a disadvantage of adhesive bonding compared to welding. The use of electromagnetic induction is a promising solution for accelerated curing. This work investigates induction heating for accelerated curing of 1-C epoxy adhesives for bonding of thin nickel foils. Process parameters for rapid curing of the adhesives were determined based on reaction kinetics using differential scanning calorimetry measurements. According to those results peel test specimens were fabricated, and the peel resistance was evaluated using a 90° peel load.

An Investigation about Microstructures, Mechanical Properties and Corrosion Behaviour of the TIG - MIG Hybrid Welded Dissimilar UNS 2205 and is 2062 Steels

The connecting of contrasting metals, namely double stainless steel to steel made of carbon, has taken place. performed using a hybrid welding system. A TIG and MIG welding joining based hybrid joining method was designed. The microstructures of the dissimilar metal joints were studied and the grains are coarser as contrast to the use of a single the welding process process by itself. With the addition of TIG welding to the process of MIG welding, the water-holding capacity of the metal in molten state pool is significantly improved. The nominal corrosion behaviour of the weldments was found better than the single arc welding system alone. The passivation behaviour of the joints was in the similar line to that of double stainless steel base metal. The pitting resistance of the joints in 1 M NaCl solution was inferior to the base metals.

Influence of Failure-Load Prediction in Composite Single-Lap Joints with Brittle and Ductile Adhesives Using Different Progressive-Damage Techniques.

The usage of adhesively bonded joints, such as single-lap and double-lap joints, is increasing rapidly in aerospace composite structures as a popular alternative to bolts and rivets. Compared to the conventional joining methods such as fastening and riveting, adhesive-bonding technology better prevents damage to composite structures due to the smooth configuration and the mitigation of stress concentration around holes. In this work, the built-in progressive-damage-modeling techniques in Abaqus, including the cohesive zone model (CZM) and the virtual crack closure technique (VCCT), are used to predict the strength and progressive failure of composite single-lap joints subjected to tensile loading. Modeling of an adhesive layer by using a zero/non-zero-thickness cohesive element, cohesive surface, and VCCT is investigated, as is the effect of brittle and ductile adhesives. Two-dimensional finite-element models with different damage-modeling strategies are performed in this study. The failure-load predictions are compared with the experimental results obtained from the literature. For the ductile adhesive, the predicted failure loads using a zero/non-zero-thickness cohesive elements and a cohesive surface are all shown to be in good agreement with the experiments. However, the VCCT technique predicts higher failure loads. For a brittle adhesive, on the other hand, the predictions by zero/non-zero-thickness cohesive elements and cohesive surfaces reveal notable deviations compared to the experimental results. In contrast to the ductile adhesive, the VCCT technique is revealed to be accurate in predicting the brittle adhesive.

A State-of-the-Art Review on Direct Welding of Polymer to Metal for Structural Applications: Part 1 — Promising Processes

Structural lightweighting through the effective use of multiple materials has received increasing attention for fulfilling today’s demands for environmental sustainability in transportation systems. Direct dissimilar material joining methods (versus, e.g., traditional adhesive bonding or mechanical fastening) have become increasingly desirable since they offer process simplicity, production efficiency, and hermetic sealing, among others. In this two-part article, we provide a critical assessment of the state-of-the-art research and promising direct dissimilar material joining techniques reported over the last decades, with a particular emphasis on their potential for structural applications in Part I. As such, recent advances in advanced joint design and modeling methods for enabling optimum joint design for jointability and joint performance are presented along with some detailed examples for demonstrating their potential impacts on industrial applications in Part II. Finally, recommendations on future research and development directions are outlined for supporting the industry’s drive towards multi-material lightweighting.

Whole genome analysis of Human Mastadenovirus D causing Keratoconjunctivitis in India - A multicentre study.

Human mastadenovirus (HAdV) types 8, 37, 64 have been considered the major contributors in Epidemic keratoconjunctivitis (EKC) epidemics, but recent surveillance data have shown the involvement of emerging recombinants, including HAdV-53, HAdV-54, and HAdV-56. In our initial work, positive samples for adenovirus revealed that our strains were closer to HAdV-54 than HAdV-8. Hence, the current study aimed to use whole genome technology to identify the HAdV strain correctly. Oxford Nanopore technique was used, wherein a Targeted sequencing approach using long-range PCR amplification was performed. Primers were designed using HAdV-54 (AB448770.2) and HAdV-8 (AB897885.1) as reference sequences. Amplicons were sequenced on the GridION sequencer. Sequences were annotated using Gatu software, and similarities with standard reference sequence was calculated using Bioedit software. The phylogenetic tree was built after alignment in MEGA v7.0 using Neighbour joining method for each of the genes: Penton, Hexon, and Fiber. The effect of novel amino acid changes was evaluated using the PROVEAN tool. The Recombination Detection Program (RDP) package Beta 4.1 was used to identify recombinant sequences. Of the five samples sequenced, OL450401, OL540403, and OL540406 showed nucleotide similarity to HAdV-54 in the penton region. Additionally, OL450401 showed a statistically significant recombination event with HAdV-54 as minor and HAdV-8 as major parents. This was further supported by phylogenetic analysis as well. In the present study, we have found evidence of a shift from HAdV-8 towards HAdV-54, thus stressing the need for surveillance of HAdVs and to stay updated on the rise of new recombinants.

Assessing Cleaning in Remanufacturing: A Case Study of Shot Blasting Efficiency to Alternator Design

Cleaning is a crucial step in the remanufacturing of end-of-life components. The main purpose of cleaning is to remove all contaminant items such as dirt, oils, dust in order to facilitate the process of core inspection before moving on to the subsequent step to complete the remanufacturing activity. However, there are issues/challenges related to the cleaning methods that affect the process efficiency. It has also been reported that the cleaning process is time consuming and has adverse impact to the environment. Cleaning is directly influenced by the various cleaning methods and the design features of each core/incoming parts. Therefore, the aim of this paper is to evaluate the effectiveness of shot blasting cleaning method from core design perspectives in the case of an alternator. The results will be assessed based cleanliness level after the cleaning process on the core surface, complex shape, geometry, and joining method. The outcome demonstrates that the complexity of the core design also affects the cleaning process efficiency. According to the study shot blasting cleaning method without any pretreatment process was insufficient to fully clean the core. Hence, it is suggested to consider several parameters to enhance the shot blasting method to clean the used alternator for remanufacturing process.

Coat protein of alfalfa mosaic alfamovirus (AMV) from Türkiye: genetic inference and in silico docking analysis for potential antiphytoviral purposes

In 2021, a study was conducted in the Denizli region of Türkiye to investigate the phylogenetic relationship and presence of alfalfa mosaic alfamovirus (AMV) infecting pepper plants exhibiting viral disease symptoms. A total of 57 samples were collected, of which twenty-four tested positive for AMV with reverse transcriptase polymerase chain reaction (RT-PCR) assays. Samples from pepper plants displaying virus symptoms gave positive bands on the agarose gel, while healthy plants yielded negative results. One of the positive samples was randomly selected, cloned and sequenced. This sequence of the Denizli AMV isolate (753 bp) was recorded in the GenBank database with accession number OQ845956. The nucleotide sequence showed a high nucleotide consensus of 97%-99% compared with the nucleotide sequences of the same variants from different origins in GenBank. According to the phylogenetic tree generated through the Neighbour Joining (NJ) method, this AMV isolate belongs to the same group as Iranian isolates from various of hosts. Furthermore, in silico docking analysis of the coat protein (CP) of the AMV isolate and promising 12 essential oil compounds was performed to enable potential antiviral drug development. Docking study showed that eucalyptol, eugenol and carvacrol can make important contributions to the advancement of drug-based strategies for the managing of plant viruses by interacting with the virus coat protein of high binding energies, -5.3, -5.2 and -5.0 kcal mol-1, respectively. Although the presence of AMV in Denizli province has been reported previously, this study reports the phylogenetic relationships and docking analysis of the new AMV isolate in pepper crops.

A Software for Optimum Design of Laterally Loaded Bolted Joints

Bolted joints, which are one of the detachable joining methods, are used extensively. The reliability of bolted joints is extremely important for the strength and life of the system. The determination of the number of bolts to be used in a system, the position and other data of the bolt requires very serious design and engineering studies. In this study, the design and optimization of bolted joints subjected to lateral forces are performed. For this purpose, a software has been developed in C# programming language. The software visually guides the user and asks a minimum number of questions to the designer and all other parameters are calculated by the program. The visual design of the program was done in Visual Studio environment. The graphic designs used in the software help the user to enter correct data. When the program is run for bolted joint under lateral loading, the user only enters the number of plates and force as input. Although the program performs its calculations between 1.5-2 factor of safety, it is possible to change it according to the characteristics of the design. The program developed in the light of these inputs calculates the appropriate bolt diameter, number, material and dimensions of the plates for the designed joint according to the optimum design options. The design options determined by the program are also presented to the designer visually. With the developed software, the user workload is minimized by determining the optimum options of bolted joints according to the minimum amount of user input. This resulted in significant savings in the time spent in design and engineering calculations. The user-friendly interface provides an easy and visual use. The results obtained by the program were also solved manually to check the reliability of the program.

Development and Analysis of GIS Regional Political Profiles in West Java Utilizing the Spatial Overlay Join Method

This research aims to build Geographic Information System (GIS) of Political Region Profiles in West Java using the Overlay Spatial Join method. The study addresses the political complexity in Indonesia, particularly in West Java, which serves as a significant political base. The success of political campaigns requires a profound understanding of voter preferences, demographic dynamics, and local issues. Limited access to accurate location data poses a serious obstacle to the effective design of campaign strategies. This research responds to these challenges by designing a GIS that integrates political and spatial data. The research focuses on West Java, where regional diversity poses unique challenges. Through the Overlay Spatial Join method, the research aims to provide in-depth insights into political region profiles, serving as a foundation for intelligent political campaign strategies. The benefits of the research include an understanding of regional characteristics, performance comparisons of political parties, and in-depth analysis for campaign resource efficiency. The system integrates data from various sources, provides spatial visualization, and enables the analysis of regional profiles for the identification of deep political information. The research's contribution is not only academic but also practical in enhancing the effectiveness of democracy and general elections in West Java.

Residual Stress Measurement Using X-ray Diffraction in Friction Stir-Welded Dissimilar Titanium Alloys.

Surface residual stresses in welded specimens significantly influence properties such as fatigue resistance, fracture toughness, and the superplasticity of joints. In this study, we employed friction stir welding, a well-established joining method, to weld dissimilar titanium alloys. By combining two distinct titanium alloys, we aimed to harness their unique properties when subjected to cyclic loading, impact, or superplastic forming processes. Utilizing X-ray diffraction, macroscopic surface stresses were assessed in dissimilar titanium alloys (Ti-6242 standard grain (SG) and Ti-54M) welded via friction stir welding, assuming a linear lattice distortion. The study accounted for misalignment, significant distortion, and grain refinement in the stir zone. Macroscopic surface residual stresses were quantified on the weld surface and at a depth of 1.5 mm beneath it within a square cross-section (1 × 1 mm2) by oscillating the specimen in the (X-Y) direction. The sin2φ method, implemented through the LEPTOS® (v7.8) software, was employed for residual stress measurement. The analysis of the results was conducted with respect to different rotation and traverse speeds. It was noted that at the center (CEN) of the weld, commonly referred to as the weld nugget, approximately 50 MPa of tensile stress was observed under the lowest values of both tool rotation speed and traverse speed. Tensile residual stresses were evident at the boundaries and within the stir zone. No discernible pattern was observed at the specified locations. Notably, the resultant values of residual stress, influenced by rotation and traverse speeds, exhibited asymmetry.

Cavity growth – or lack thereof – in imperfectly roll bonded sheet metal

Roll bonding is a well-established solid-state joining method that has also found commercial use. In current industrial practice, a near-perfectly bonded interface is commonly aimed for, achieved by optimizing surface preparation and rolling parameters. On the other hand, an intriguing recent study has shown that roll bonding scrap metal has the potential to provide significant environmental benefits while not jeopardizing performance, despite the resulting imperfect interface with a distribution of cavities. This present work focuses on the mechanical aspects of this observation, aiming to provide a deeper understanding of the influence (or lack thereof) of the cavity content on the mechanical behavior of a roll bonded stainless steel, and a roll bonded mild steel. Imperfectly bonded samples of both steels are studied using mechanical tests and microstructure characterization, which both revealed that the interface cavities exhibit limited growth and no crack nucleation or propagation into the interface. A numerical finite element model of the imperfectly bonded sheet confirmed a tendency for low cavity growth by showing that opening stresses on the interface cavity remain low for various geometries and loading conditions, in line with linear elastic fracture mechanics calculations. Overall, this experimental-numerical study provides insights regarding the unexpected formability (and thus the wide applicability) of imperfectly roll bonded sheets.