• Title, Summary, Keyword: Low Melting Alloys

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Microstructures and Solderability of Multi-composition Sn-Cu Lead-free Solders (Sn-CU계 다원 무연솔더의 미세구조와 납땜특성)

  • Kim Ju-Youn;Bae Kyoo-Sik
    • Korean Journal of Materials Research
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    • v.15 no.9
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    • pp.598-603
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    • 2005
  • To develope new lead-free solders with the melting temperature close to that of Sn-37Pb$(183^{\circ}C)$, Sn-0.7Cu-5Pb-1Ga, Sn-0.7Cu-5Pb-1Ag, Sn-0.7Cu-5Pb-5Bi-1Ag, and Sn-0.7Cu-SBi-1Ag alloys were composed by adding low-netting elements such as Ga, Bi, Pb, and Ag to Sn-0.7Cu. Then the melting temperatures, microstructures, wettability, and adhesion properties of these alloys were evaluated. DSC analysis showed that the melting temperature of Sn-0.7Cu-SPb-1Ga was $211^{\circ}C$, and those of other alloys was in the range of $192\~200^{\circ}C$. Microstructures of these alloys after heat-treatment at $150^{\circ}C$ for 24 hrs were basically composed of coarsely- grown $\beta-Sn$ grains, and $Cu_6Sn_5$ and $Ag_3Sn$ intermetallic precipitates. Sn-0.7Cu-5Pb-1Ga and Sn-0.7Cu-5Pb-5Bi-1Ag showed excellent wettability, while Sn-0.7Cu-5Bi-1Ag and Sn-0.7Cu-5Pb-5Bi-1Ag revealed good adhesion strength with the Cu substrates. Among 4 alloys, Sn-0.7Cu-5Pb-5Bi-1Ag with the lowest melting temperature $(192^{\circ}C)$ and relatively excellent wettability and adhesion strength was suggested to be the best candidate solder to replace Sn-37Pb.

The Effect of Electromagnetic Stirring on the Semi-Solid Microstructure of Cu-0.15wt%Zr Alloy (전자교반에 의한 Cu-0.5wt%Zr 합금의 반응고 조직제어에 관한 연구)

  • Lim, Sung-Chul;Lee, Heung-Bok;Kim, Kyung-Hoon;Kwon, Hyuk-Chon;Yoon, Eui-Pak
    • Journal of Korea Foundry Society
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    • v.26 no.1
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    • pp.40-45
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    • 2006
  • Most of the work reported concerned the semi-solid processing of low melting point alloys, and in particular light alloys of aluminum and magnesium. The purpose of this paper is to develop a semi-solid microstructure of Cu alloys using electromagnetic stirring applicable for squirrel cage rotor of induction motor. The size of primary solid particle and the degree of sphericity as a function of the variation in cooling rate, stirring speed, and holding time were observed. By applying electromagnetic stirring, primary solid particles became finer and rounder relative to as-cast sample. As the input frequency increased from 30 to 40 Hz, particle size decreased. The size of primary solid particle was found to be decreased with increasing cooling rate. Also, it decreased with stirring up to 3 minutes but increased above that point. The degree of sphericity became closer to be 1 with hold time. Semi-solid microstructure of Cu alloys, one of the high melting point alloys, could be controlled by electromagnetic stirring.

The Effect of Low Melting Point Phase on Mechanical Properties of Al-Cu-Li-X(In, Be) Alloys (Al-Cu-Li-X(In, Be) 합금의 기계적 성질에 미치는 저융점상의 영향)

  • Lee, J.S.;Lee, S.H.;Kim, S.W.;Woo, K.D.
    • Journal of the Korean Society for Heat Treatment
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    • v.8 no.4
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    • pp.245-254
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    • 1995
  • The purpose of this study was to examine the effects of low melting point phase(LMPP) on mechanical properties in the Al-Cu-Li-X(In, Be) alloys. This study was performed by the differential scanning calorimetry(DSC), the transmission electron microscope(TEM), hardness test, tensile test and notch tensile test. The shape of LMPP in the specimens homogenized at $570^{\circ}C$ was film type due to remelting at grain boundary during homogenization. Low melting point phases had no effects on mechanical properties in the aging treated materials, because the density of LMPPs was low. Mechanical properties of the aging treated materials were affected by the density of matrix precipitation phases and grain sizes. For the In or In, Be added Al-Cu-Li alloys, the optimum solution treatment temperature was $550^{\circ}C$. The strength of Al-Cu-Li-In-Be $T_6$ treated alloy was higher than that of 2090-$T_8$ alloy.

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Hardness and Microstructures of Ti-Zr-(Cu) based Alloys for Dental Castings (치과주조용 Ti-Zr-(Cu)계 합금의 경도 및 미세조직)

  • Joo, Kyu-Ji
    • The Journal of Korean Academy of Dental Technology
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    • v.27 no.1
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    • pp.65-71
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    • 2005
  • Experimental Ti-13%Zr and Ti-13%Zr-5%Cu alloys were made in an argon-arc melting furnace. The grade 2 CP Ti was used to control. The alloys were cast into phosphate bonded $SiO_2$ investment molds using an argon-arc casting machine, and The hardness and microstructures of the castings were investigated in order to reveal their possible use for new dental casting materials and to collect useful data for alloy design. The hardness of the Ti-13%Zr-5%Cu alloy(379Hv) became higher than that of Ti-13%Zr(317Hv) alloy, and the hardness of this alloys became higher than that of CP Ti(247Hv). Increasing in the hardness of the Ti-13%Zr-5%Cu alloy was considered to be solid solution hardening as the Ti-Zr system shows a completely solid solution for both high temperature $\beta$phase and low temperature $\alpha$ phase and also the inclusion of the eutectoid structure($\alpha Ti+Ti_{2}Cu$). No martensitic structures are observed in the specimen made of CP Ti, but Ti-13%Zr and Ti-13%Zr-5%Cu alloys show a kind of martensitic structure. Ti-13%Zr-5%Cu shows the finest microstructure. From these results, it was concluded that new alloys for dental casting materials should be designed as Ti-Zr-Cu based alloys.

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Conductive Inks Manufactured with the Help of Low Melting Metals (용해도 낮은 금속을 이용한 전기 전도성 잉크)

  • Han, Kenneth N.;Kim, Nam-Soo
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.1
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    • pp.126-131
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    • 2008
  • In this investigation, various factors affecting manufacturing conductive inks are presented, examined and discussed. The discussion includes inherent difficulties in making conductive inks successful and at the same time offers ways in which these difficulties might be overcome. One of the solutions to overcome such difficulties is to use low melting metals and alloys. This aspect is also detailed.

Enhancement of Wetting Characteristics for Anisotropic Conductive Adhesive with Low Melting Point Solder via Carboxylic Acid-based Novel Reductants (카르복실산계 환원제를 통한 저융점 솔더입자가 포함된 이방성 전도성 접착제의 젖음 특성 향상 연구)

  • Kim, Hyo-Mi;Kim, Joo-Heon
    • Polymer Korea
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    • v.34 no.1
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    • pp.52-57
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    • 2010
  • The low viscous epoxy resin(bisphenol F) with carboxylic acid as the reductants was introduced for high performance and reliability in the ACA with a low melting point alloy filler system. The curing characteristics of the epoxy resin and temperature dependant viscosity characteristic of epoxy resin at the melting temperature of LMPA were investigated by dynamic mode of differential scanning calorimetry (DSC) and rheometer, respectively. Based on these thermo-rheological characteristics of epoxy resin and LMPA, the optimum process system was designed. In order to remove the oxide layer on the surface of LMPA particle, three different types of carboxyl acid-based reductant were added to the epoxy resin. The wetting angles were about $18^{\circ}$ for carboxypropyldisilioxane, and $20.3^{\circ}$ for the carboxy-2-methylethylsiloxane, respectively.

Rapid Manufacturing of Microscale Thin-walled Structures using a Phase Change Work-holding Method

  • Shin Bo-Sung;Yang Dong-Yol
    • International Journal of Precision Engineering and Manufacturing
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    • v.7 no.3
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    • pp.47-50
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    • 2006
  • High-speed machining is a very useful tool and one of the most effective rapid manufacturing processes. This study sought to produce various high-speed machining materials with excellent quality and dimensional accuracy. However, high-speed machining is not suitable for microscale thin-walled structures because the structure stiffness lacks the ability to resist the cutting force. This paper proposes a new method that is able to rapidly produce very thin-walled structures. This method consists of high-speed machining followed by filling. A strong work-holding force results from the solidification of the filling materials. Low-melting point metal alloys are used to minimize the thermal effects during phase changes and to hold the arbitrarily shaped thin-walled structures quickly during the high-speed machining. We demonstrate some applications, such as thin-walled cylinders and hemispherical shells, to verify the usefulness of this method and compare the analyzed dimensional accuracy of typical parts of the structures.

Rapid Manufacturing of Microscale Thin-walled Structures by Phase Change Workholding Method (상변화 고정방식에 의한 마이크로 박벽 구조물의 쾌속제작)

  • Shin, Bo-Sung
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.9
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    • pp.188-193
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    • 2005
  • To provide the various machining materials with excellent quality and dimensional accuracy, high -speed machining is very useful tool as one of the most effective rapid manufacturing processes. However, high-speed machining is not suitable for microscale thin-walled structures because of the lack of the structure stiffness to resist the cutting force. A new method which is able to make a very thin-walled structure rapidly will be proposed in this paper. This method is composed two processes, high-speed machining and filling process. Strong workholding force comes out of the solidification of filling materials. Low-melting point metal alloys are used in order to minimize the thermal effect during phase change and to hold arbitrary shape thin-walled structures quickly during high-speed machining. To verify the usefulness of this method, we will show some applications, for examples thin -wall cylinders and hemispherical shells, and compare the experimental results to analyze the dimensional accuracy of typical parts of the structures.

Influence of Various Additional Elements in Al Based Filler Alloys for Automotive and Brazing Industry

  • Sharma, Ashutosh;Shin, Y.S.;Jung, Jae-Pil
    • Journal of Welding and Joining
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    • v.33 no.5
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    • pp.1-8
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    • 2015
  • Aluminium and its alloys are widely used in brazing various components in automotive industries due to their properties like lightweight, excellent ductility, malleability and formability, high oxidation and corrosion resistance, and high electrical and thermal conductivity. However, high machinability and strength of aluminium alloys are a serious concern during casting operations. The generation of porosity caused by dissolved gases and modifiers affects seriously the strength and quality of cast product. Brazing of Al and its alloys requires careful monitoring of temperature since theses alloys are brazed at around the melting temperature in most of the aluminium alloys. Therefore, the development of low temperature brazing filler alloys as well as superior strength Al alloys for various engineering applications is always in demand. In various heat exchangers and automotive applications, poor strength of Al alloys is due to the inherent porosities and casting defects. The unstable mechanical properties is therefore needed to be controlled by adding various additive elements in the aluminium and its alloys, by a change in the heat treatment procedure or by modifying the microstructure. In this regard, this article reports the effect of various elements added in aluminium alloys to improve microstructure, brazeability, machinability, castability as well as to stabilize the mechanical properties.