The objective of the present study was to join silicon nitride ceramic (Si3N4) to molybdenum using a BRAZING technique. A commercially available Ag- Cu-Ti BRAZING alloy (Cusil-ABA) was used as the filler metal. Using sessile drop method, it was found that the Cusil alloy was able to wet Si3N4 adequately. Joining experiments were performed at 900°C. The results of the study showed that Si3N4 can be brazed to Mo using Cusil-ABA with no sever degradation of the parent materials. The room temperature four-point bend strength of the Si3N4-Mo joints was found to be about 390 MPa.

Lap joint poly composites of base-clad AA3003/AA4043 alloys have been prepared in various conditions after vacuum furnace BRAZING at a pressure setting of 5×10-5 mbar. Shear strength of basements were measured under tensile loading. The results show that the bond strength decreases by increasing the length of lap joint. The maximum peeling strength was obtained at a critical length (2mm) of overlap using a clad thickness of 50- 100 μm. Sagging resistance of BRAZING sheets was independent of reduction in area due to low Si content of braze material. Fracture surfaces of the samples show two different ductile and brittle regions. Due to results of the energy dispersive X-ray analyses (EDX), brittle fracture regions have more Si content than the ductile fracture regions.

BRAZING of low-carbon austenitic stainless steel sheets is applied to produce plate heat exchangers. In this study, the copper filler was used to join multiple layers of 316L steel plates due to its low cost, low melting temperature and relatively good bonding strength compared to other filler metals. For comparison, 2-layer and 5-layer specimens were brazed with the copper interlayer. fabricated. The sandwich joints have been fabricated under different process conditions of the BRAZING temperature (1070 and 1120°C) and the BRAZING time (30, 60, and 90 min). Detailed microstructural studies and hardness were carried out on the brazed joints. The microscopic studies showed that the joint formed at 1070 °C was not uniform compared to 1120 °C and the specimen brazed at 1120°C/90 min presented better properties due to enough time for melting of the interlayer and diffusion of elements. Also, 2-layer specimens with lower average grain size had higher hardness than 5-layer specimens.

In this research work, composite BRAZING sheets of 3003/4043 aluminum alloys were made by cold roll bonding. Peel test specimens were prepared from the welded composites and annealed in 400°C for 20-80 min. Bonding strength of the BRAZING sheets was measured by peel test. Maximum peeling strength was obtained under 70 % reduction in area after annealing for 40 min at 400°C.

Both Zirconium-based alloys and 321 stainless steel are widely used as engineering alloys due to their good mechanical properties. Conventional fusion welding techniques for Zr alloys and stainless steel are not feasible due to the formation of brittle intermetallic compounds such as (Zr3Fe, ZrFe2 and Zr2Fe) and corrosion cracking. BRAZING is one of the most widely used techniques for joining dissimilar alloys.Using titanium base filler metal decreases the diffusion and the formation of brittle intermetallic compounds. In this study, wetting experiments were done at 820, 850, 865oC and 3, 5, 7 and 10 min. Also, joining of these two alloys was carried out at 850 and 865oC for 10 and 15 minutes. Optical microscope, scanning electron microscope (SEM), XRD, shear test and micro-hardness test were used for metallurgical and mechanical investigations. The results show that 20oC/min heating and cooling rates at 850oC and 10 min BRAZING condition lead to a proper joint without any brittle intermetallic compounds.

The use of lattice structures has always been envisaged by researchers and various industries because of their unique mechanical properties and low weight. One of the main challenges in this area is the manufacturing process of these structures, particularly in mass production and commercialization. Pyramid-metal tubular lattice structures are among the most optimal lattice structures for energy absorption. The connection of tubes to metal plates is one of the main challenges in the construction of these types of structures. In this research, rather than using metal molds and fixtures, the toothed appendages are created by cutting the ends of the tube and place them in the holes of the plates in order to fix the position of the tubes in the BRAZING process. Mechanical locking of tubes and plates enhances connection strength and structural stiffness. In this study, specimens have been made with various geometries and the effect of geometrical parameters such as the length to diameter ratio of the tube and its angle of orientation on energy absorption were investigated. The manufacturing process used in this research was very efficient and none of the samples were damaged at the joint. Increasing the orientation angle from 45 to 55 increases the specific energy uptake by up to 40%.

In this research, the parameters of BRAZING temperature, time, and joint seam have been optimized in BRAZING joints of 420 stainless steel with BNi-2 filler metal on the shear strength of lap joint samples using response surface methodology. The parameters of BRAZING temperature, time, and joint seam were determined by the design of the experiment using the Benken box method. The thickness of BNi-2 filler metal was considered to be 0.04, 0.07, and 0.1 mm in this research. After preparing the samples, they were placed in a vacuum furnace at temperatures of 1000°C, 1070°C, and 1140°C for 10, 30, and 50 minutes. The mechanical tensile test was performed to determine the shear strength. It was observed that increasing the joint seam from 0.04 to 0.1 mm caused a 14% decrease in shear strength. Also, increasing the BRAZING temperature from 1000°C to 1140°C has increased the shear strength by 21%, and increasing the BRAZING time from 10 to 50 minutes has increased the shear strength by 27%. In the end, it was optimized that the maximum shear strength is 164.429 MPa in the joint seam of 0.04 mm, the temperature is 1109.84 °C and the time is 46.58 minutes.

Joining of titanium alloys to other materials especially steels has attracted much attention in recent years due to the exceptional properties of titanium such as excellent corrosion resistance and mechanical properties and its increasing application in various industries. According to the Fe-Ti binary phase diagram, these two elements do not have complete solubility. This leads to difficulties during fusion welding of these two alloy. One of the best methods for joining dissimilar alloys is BRAZING. In this research, the metallurgical and mechanical properties of BRAZING lap joints of steel to commercially pure titanium using a commercial filler metal (BAg-8) made under different time and temperature conditions were investigated. The study of the microstructure interface shows the formation of a chemical layer close to the titanium side of the joint, while no chemical compounds were created on the steel side. A coarse structure is formed at the interface between the steel and silver solder alloy. The observed coarse grain structure is related to the grain growth along with recrystallization in the steel substrate at high temperatures. Analysis of the joints was carried out by optical microscopy, scanning electron microscopy, X-ray diffraction and hardness measurements. The results show that with increasing temperature, as well as BRAZING time, the average shear strength decreases due to the increased thickness of the intermediate layer.

Today, the demand for joining dissimilar metals of aluminium and steel to reduce the vehicle weight in the automotive, aerospace and shipbuilding industries has witnessed rapid growth. In the present study, 5083 aluminum alloy was joined to galvanized steel and plain carbon steel with 4043 and 4047 filler metals by using the welding-BRAZING hybrid method. The brittle intermetallic compound (IMCs) layer formed in the interface of steel-weld seam was found to have significant influence on the joint strength. The results also indicated that increasing heat input enhanced the thickness of IMCs layer. The thickness of IMCs layers, as measured from microstructural images, was in range of 2-6 mm. Further, the results obtained from microstructural observation showed that with equal weld heat input, the thickness of IMCs layer for the joint produced with 4047 filler metal was approximately half of that obtained for the joint produced with 4043 filler metal. The highest mechanical resistance (of about 170 MPa) was obtained for aluminum to galvanized steel joint with 4047 filler metal. Moreover, in this joint, the failures occurred in the welded seam and for aluminum to plain carbon steel joint, it was in the interface of steel-weld seam. The results obtained by Energy dispersive x-ray spectrometry analysis of IMCs layer for aluminum to galvanized steel joint showed the presence of the FeAl3 intermetallic compound. This was confirmed by x-ray diffraction analysis of the fracture plane.

In this study, using Ag-Cu BRAZING metal alloy, effects of BRAZING time on microstructure and strength of Al2O3 / Ti6Al4V joints were investigated. Therefore, ceramic/metal couple brazed by electrical furnace. Then, brazed specimens were examined by scanning electron microscope and x-ray diffraction tests. Several phases observed at the interface area and EDS analysis were recognized titanium, copper, silver, aluminum, vanadium and oxygen in this phases. With more study using x-ray diffraction patterns and phases diagrams some intermetallic compounds identified. This compounds were Ti-Cu intermetallices near to Ti6Al4V side and reactive layer of Cu2O +CuAlO2 near to Al2O3 ceramic side. Also, microstructural surveys revealed the narrow reaction layer and a little intermetallic compounds in specimen brazed for 10 minutes. With increasing BRAZING time, reaction layers grossed rapidly. This chemical variation made dimensional changes at metal/ceramic interface. Therefore, some crakes observed in specimen brazed for 25 minutes. Maximum of shear strength equal 295 Mpa measured in specimen brazed for 15 minutes.