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A New Technique for Brazing Porous Copper to Copper Substrate Using CuNiSnP Amorphous Filler Metal
(2025-11-01)
Mookam, Niwat
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Jattakul, Prajak
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Ariga, Tadashi
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Kanlayasiri, Kannachai
Furnace brazing is a common method for bonding porous metal to a substrate. However, it typically involves lengthy brazing times. This research introduces a novel rapid brazing technique to join porous copper to copper substrates. Using CuNiSnP amorphous filler metal, porous copper specimens were brazed under varying currents (250-1000 A) and times (900-1100 ms). Results showed successful joining without macroscopic deformation of the porous copper, and the brazing times were significantly shorter than those of traditional methods. Microstructural analysis revealed primary alpha, primary beta, and eutectic structures in the joint, all of which were influenced by brazing current and time. Adjusting the brazing conditions altered the morphology of the primary alpha structure, ranging from equiaxed to columnar dendrites, which in turn affected the joint's mechanical properties. The proposed technique offers an efficient method to manipulate joint microstructures for bonding porous copper to copper substrates, potentially improving manufacturing efficiency in industries such as heat exchangers or catalytic converters.
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Influence of electrode shape and material on shear force and microstructure of resistance spot welded AZ80 magnesium alloy
(2025-01-05)
Sangrayub, Phoometh
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Kanlayasiri, Kannachai
Resistance spot welding of AZ80 magnesium alloy is challenging owing to limited understanding of how electrode design and welding parameters interact to influence joint microstructure and strength. This study investigates the effects of electrode shape and material on the shear force and microstructure of resistance spot-welded AZ80 magnesium alloy. Three electrode shapes (A, R, and P) and two electrode materials (ZrCrCu and Al<inf>2</inf>O<inf>3</inf>Cu) were analyzed at welding currents of 13 kA and 17 kA. Nugget size and failure modes were also examined. The results demonstrate that electrode shape and material significantly affect welding heat, nugget size, and joint strength. The fusion zone (FZ) area increased due to the combined effects of welding current, electrode shape, and material. Higher welding heat modified the FZ boundary microstructure, transitioning from cellular morphologies to columnar dendrites, and eventually to equiaxed dendrites, thereby enhancing joint strength. The highest shear force was observed with an R-shaped ZrCrCu electrode at a welding current of 17 kA. However, excessive welding heat reduced the FZ area due to molten metal expulsion. It also promoted the growth of the brittle β-Mg<inf>17</inf>Al<inf>12</inf> phase in the coarse grain heat-affected zone (CGHAZ), shifting the fracture pattern from nugget pull-out to through-thickness in the base metal and decreasing joint strength. This study concludes that selecting appropriate electrodes can mitigate β-Mg<inf>17</inf>Al<inf>12</inf> phase growth in the CGHAZ, highlighting the importance of optimizing welding parameters for improved joint quality in AZ80 magnesium alloy welding.
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Optimization of the Solid-State Copper Brazing Condition Using Desirability Function and Genetic Algorithm
(2024-11-01)
Jattakul, Prajak
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Mhoraksa, Thiti
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Kanlayasiri, Kannachai
This research studies on optimization of solid-state copper brazing condition and comparatively investigates the ability of the desirability function and genetic algorithm (GA) optimization schemes with regard to the optimal brazing condition that yields the maximum brazed-joint tensile shear force, where the brazing parameters included the brazing temperature, holding time and loading pressure. To that end, a second-order mathematical model was first derived based on the Box–Behnken experimental design and the maximum-response desirability function. The findings suggested that the tensile shear force of the brazed joints was significantly influenced by all three brazing parameters. The optimal brazing condition was at 620 °C brazing temperature, 30-min holding time and 12.173 kPa loading pressure. The desirability function- and GA-predicted optimal brazing conditions were effectively identical, thus confirming the comparable power of both optimization schemes. Further experiments were conducted to validate the optimization outcomes, whereby the confirmation tests were carried out under the optimal brazing condition. The results suggest that both optimization schemes are viable for solid-state copper brazing, with the GA demonstrating a slightly higher prediction accuracy.
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EFFECT OF DIPPING SOLDERING ON THICKNESS AND INTERMETALLIC COMPOUND MORPHOLOGY BETWEEN Sn-3.0Cu LEAD-FREE SOLDER AND COPPER SUBSTRATE
(2022-01-01)
Mookam, Niwat
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Kanlayasiri, Kannachai
The thickness and morphology of intermetallic compounds formed between Sn-3.0Cu lead-free solder and the copper substrate were investigated. In the experiment, the dipping soldering was performed at 350°C using Sn-3.0Cu lead-free solder for various dipping time lengths of 5, 10, 20, 50, 75 and 100s, respectively. The results indicated that η- Cu6Sn5 intermetallic phase was found to exist between the lead-free solder and the copper substrate. The formation of an ε-Cu3Sn particles on the η- Cu6Sn5 surface and grain boundary was found only when the substrate was soldered for 75 and 100s. The long soldering time and formation of ε-Cu3Sn particles resulted in the morphology of the η- Cu6Sn5 IMC changed from scallop shape to more round. Nevertheless, the thickness and morphology of intermetallic compounds was also found to be influenced by the diffusion controlled process.
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Effects of Ni Content on Melting Behaviors and Wettability of SnBiAgNi Lead-Free Solder
(2022-01-01)
Mookam, Niwat
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Jattakul, Prajak
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Kanlayasiri, Kannachai
This research aimed to study the effects of Ni content on melting behaviors and wettability of SnBiAgNi lead-free solder. Sn-58Bi-0.05Ag was used as the base solder, and Ni was then put in by 0.05, 0.10, 0.50 or 1.00 wt%. Solidus and liquidus temperatures of the solder alloys were examined to study melting behaviors. The Ni content changed the solidus and liquidus temperatures, and Sn-58Bi-0.05Ag-0.10Ni possessed the lowest solidus and liquidus temperatures. Sn-58Bi-0.05Ag-0.10Ni also provided the narrowest pasty range. Wettability of the solders on the copper substrate was expressed in terms of spread factor. The addition of Ni improved the wettability of the base solder, and Sn-58Bi-0.05Ag-0.10Ni provided the highest spread factor.
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Investigation of Contact Angles of SnAgCu Solder Paste Mixed with Graphene Oxide Using Digital Holography Technique
(2021-01-20)
Jongjinakool, Kavisra
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Prakobsang, Tawipon
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Plaipichit, Suwan
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Kanlayasiri, Kannachai
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Kitiwan, Mettaya
Since lead is a pollutant to the environment, therefore lead-free solder paste compounds have been interested in many research teams. The objective of this research is the investigation properties of solder paste with graphene oxide and reduced graphene oxide. In our experimental method the solder pastes of SnAgCu mixed with graphene oxide with bad electrical conductivity at different concentration by weight of 0.00%, 0.05%, 0.1% and 0.2% respectively. Subsequently, the shape changes of the compounds have been investigated by using digital in-line holography using laser diode wavelength 635 nm as the light source. The solder paste compounds were melted at 250 ± 5 °C and were recorded for every 5 seconds. Then, the contact angles of the melted solder paste compound have been determined using their digital holographic reconstructed images.
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Effects of side flushing and multi-aperture inner flushing on characteristics of electrical discharge machining macro deep holes
(2021-01-01)
Chuvaree, Suppawat
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Kanlayasiri, Kannachai
This research investigates the effect of machining parameters on material removal rate, electrode wear ratio, and gap clearance of macro deep holes with a depth-to-diameter ratio over four. The experiments were carried out using electrical discharge machining with side flushing and multi-aperture flushing to improve the machining performance and surface integrity. The machining parameters were pulse on-time, pulse off-time, current, and electrode rotation. Response surface methodology and the desirability function were used to optimize the electrical discharge machining parameters. The results showed that pulse on-time, current, and electrode rotation were positively correlated with the material removal rate. The electrode wear ratio was inversely correlated with pulse on-time and electrode rotation but positively correlated with current. Gap clearance was positively correlated with pulse on-time but inversely correlated with pulse off-time, current, and electrode rotation. The optimal machining condition of electrical discharge machining with side flushing was 100 µs pulse on-time, 20 µs pulse off-time, 15 A current, and 70 rpm electrode rotation; and that of electrical discharge machining with multi-aperture flushing was 130 µs, 2 µs, 15 A, and 70 rpm. The novelty of this research lies in the use of multi-aperture flushing to improve the machining performance, enable a more uniform GC profile, and minimize the incidence of recast layer.
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Brazing of Porous Copper Foam with Copper Sheet Using CuNiSnP Amorphous Filler Metal
(2021-01-01)
Mookam, Niwat
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Jattakul, Prajak
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Rakphet, Tipsuda
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Kanlayasiri, Kannachai
This research studies effects of the brazing time on interfacial microstructure of brazed joint between the porous copper foam (PCF) and Cu substrate using CuNiSnP amorphous filler metal. To examine the interfacial microstructure and its properties, an assessment of PCF/CuNiSnP/Cu brazed joints was conducted after electric furnace brazing under hydrogen (H2) atmosphere. The results showed that the interfacial microstructure was thick for short brazing time specimens and thin for prolonged brazing time specimens. The interfacial microstructures consisted of Cu-rich solid solution, (Cu, Ni)3P, and Cu3P as a eutectic structure discovered in the brazing region at different brazing times of 5, 10, and 20 min. Only the Cu-rich solid solution and (Cu, Ni)3P were found in the specimen with brazing time of 30 min. indicating that different brazing times affected interfacial microstructures and therefore reliability of the brazed joints.
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Contact Angle Measurement of Melting SnAgCu Solder Paste Mix with Carbon Allotropes Using In-Line Digital Holography Technique
(2021-01-01)
Mamart, Wikatsama
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Somdock, Nuttakrit
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Boonsri, Chantira
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Plaipichit, Suwan
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Buranasiri, Prathan
In this research we investigated the contact angle of commercial SnAgCu solder paste mixing with some carbon allotropes such as graphite, graphene quantum dots, and fullerene of varying concentrations with melting temperature, wettability, interfacial microstructure. The wettability was assessed in terms of the contact angle. The in-line digital holography was used for determining the contact angle and morphological of samples at each temperature which the samples have been heating from room temperature until the melting temperature. In the experiment, only one beam was used as the object and reference beams which recorded by a CMOS camera. The recorded image was reconstructed by the angular spectrum digital holography numerical programing. Using the reconstructed images of our results, the shape and contact angle of solder pastes can be investigated.
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Effect of bending temperatures on the microstructure and springback of a TRIP steel sheet
(2020-10-01)
Pornputsiri, Natthasak
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Kanlayasiri, Kannachai
Transformation-induced plasticity (TRIP) steel possesses high strength and formability, enabling the use of a thinner gauge material and allowing for the fabrication of complex shapes. In this research, we measured the effect of bending temperatures on the microstructure and air-bending springback angle of TRIP steel at temperatures from 25 to 600 °C. Real-time in situ X-ray diffraction and scanning electron microscopy were used for pre- and postbending analysis. As the prebending temperature increased from 25 °C to 600 °C, the retained austenite (RA) volume fraction decreased, and the RA transformed to bainite at temperatures above 400 °C. The springback angle was positively correlated with the prebending RA volume fraction, with the smallest springback angle achieved at 400 °C. Additionally, the springback angle was positively correlated with the bending angle, because the RA transformation ratio contributed to increased strain hardening. Further microstructure analysis revealed that the RA became elongated in the tension direction as the bending temperatures increased.

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