KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 8 of 8

Some of the metrics are blocked by your
consent settings
A New Technique for Brazing Porous Copper to Copper Substrate Using CuNiSnP Amorphous Filler Metal
(2025-11-01)
Mookam, Niwat
;
Jattakul, Prajak
;
Ariga, Tadashi
;
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.
Some of the metrics are blocked by your
consent settings
Optimization of the Solid-State Copper Brazing Condition Using Desirability Function and Genetic Algorithm
(2024-11-01)
Jattakul, Prajak
;
Mhoraksa, Thiti
;
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.
Some of the metrics are blocked by your
consent settings
Effects of Ni Content on Melting Behaviors and Wettability of SnBiAgNi Lead-Free Solder
(2022-01-01)
Mookam, Niwat
;
Jattakul, Prajak
;
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.
Some of the metrics are blocked by your
consent settings
Influence of cooling conditions on microstructure and mechanical property of Sn-0.3Ag-0.7Cu lead-free solder
(2021-01-01)
Jattakul, Prajak
;
Madsa, Tavee
;
Sunasuan, Piyawan
;
Mookam, Niwat
This research has investigated the influence of cooling conditions on the microstructure and mechanical properties i.e., tensile strength and microhardness of Sn-0.3Ag-0.7Cu lead-free solder. In the experiments, casting was performed at 300°C with comparison between copper and stainless steel molds under slow and fast cooled conditions. X-ray diffractometer confirmed the presence of Cu6Sn5 and Ag3Sn phases in the solder matrix. Lead-free solder solidified under slow cooled conditions exhibited β-Sn matrix with larger grain growth as compared to the fast cooled solder. The eutectic area of intermetallic compound (IMC) was found to increase with cooling rate. The tensile strength of slow cooled solder was greater than fast cooled solder for both molds. In addition, the microhardness of the solder was also influenced by cooling rate. The dimples size of facture surface was decreased by higher cooling rate. A greater eutectic area of the Cu6Sn5 and Ag3Sn phases of initial β-Sn matrix lead to lower values of the mechanical property from fast cooled conditions.
Some of the metrics are blocked by your
consent settings
Brazing of Porous Copper Foam with Copper Sheet Using CuNiSnP Amorphous Filler Metal
(2021-01-01)
Mookam, Niwat
;
Jattakul, Prajak
;
Rakphet, Tipsuda
;
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.
Some of the metrics are blocked by your
consent settings
Brazing of curved copper sheets using CuNiSnP amorphous filler metal
(2019-09-30)
Jattakul, Prajak
;
Kanlayasiri, Kannachai
This research investigates the effect of bending stress using furnace brazing on the interfacial layer between curved copper sheets and CuNiSnP amorphous filler metal. Copper sheet curvatures were varied between 5, 10, 15, 20, and ∞ mm to manipulate the bending stress of the base metal. The thermal behaviors and phase transformations of CuNiSnP amorphous filler metal were also characterized. The results showed that crystallization of the filler metal started at 200 °C, with multiple phases formed over the course of thermal treatment. The curved radius and bending stress were inversely correlated, while the interfacial layer of brazed joints and copper sheet curvatures were positively correlated. The interfacial layer was thin in small curvature specimens and thick in large radius specimens, indicating that the bending stress in the base metal affected the reliability of brazed joints.
Some of the metrics are blocked by your
consent settings
Effects of brazing parameters on the microstructure and tensile shear force of copper sheets using amorphous filler metal
(2018-08-14)
Jattakul, Prajak
;
Kanlayasiri, Kannachai
In this research, the objective was to investigate and measure the microstructure, tensile shear force, and fracture surface behavior when copper sheets are brazed using Cu-Ni-Sn-P amorphous filler metal. In order to examine the microstructure and its properties, assessment of the Cu-Ni-Sn-P/copper brazed joints was conducted after furnace brazing under an argon atmosphere using specific parameters relating to temperature, holding time, and loading pressure. In order to assess the tensile shear force, tensile testing was carried out. All the joints exhibited sound bonding without voids or cracks, when brazing temperatures reached 680 °C, this resulted in a maximum value for tensile shear force of 696.325 N. The microstructure consisted of both Cu-rich solid solution and a (Cu, Ni)<inf>3</inf>P phase as a eutectic structure formed in the brazing joint, and then the Cu-rich solid solution was produced as a matrix region around the eutectic structure. Fracture analysis was conducted for brazed joints which showed the ductile fractures after the shear test.
Some of the metrics are blocked by your
consent settings
Simultaneous optimization of dimensional accuracy and surface roughness for finishing cut of wire-EDMed K460 tool steel
(2013-07-01)
Kanlayasiri, Kannachai
;
Jattakul, Prajak
The aim of this research was to determine an optimal cutting condition of dimensional accuracy and surface roughness for finishing cut of wire-EDMed K460 tool steel. The cutting variables investigated in this study encompassed cutting speed, peak current, and offset distance. Box-Behnken design was employed as the experimental strategy, and multiple response optimization on dimensional accuracy and surface roughness was performed using the desirability function. Results showed that both peak current and offset distance have a significant effect on the dimension of the specimen while peak current alone affects the surface roughness. The optimal cutting condition was at 2 A peak current and 772 μm offset distance. Since neither dimension nor surface roughness was affected by cutting speed, the speed was thus set at the highest of 5.5 mm/min to maximize the production rate. Confirmation tests on the optimal cutting condition were executed by which all cut specimens were shown to be within the specifications. © 2013 Elsevier Inc.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results