• 비파괴검사학회지
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• 제27권5호
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• pp.426-431
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• 2007

고에너지 초음파 여기 탄성파가 물체의 균열, 박리 등의 결함 부위를 통과할 때 서로 맞닿은 결함면은 균일하게 진동하지 않는다. 초음파 입사에 따른 결함 면 사이의 마찰(friction), 문지름 (rubbing) 또는 부딪침(clapping) 에 의해 진동 에너지가 결함 부위에서 국부적인 열로 변환된다. 이를 적외선 열 영상 카메라로 관측하면 구조물의 결함을 실시간으로 검출할 수 있다. 본 논문에서는 초음파 열 영상 검사를 이용한 인코넬 합금 박판의 브레이징 접합 결함 검출에 대해 기술한다. 2 kW 의 전력과 23 kHz 대역의 가진 주파수를 갖는 초음파 펄스를 280 ms 기간 동안 인코넬 합금의 브레이징 접합 박판에 입사시켰다. 브레이징 접합부의 결함위치 부근의 인코넬 합금 박판의 양면이 맞닿은 경계선에서 아주 밝은 국부적인 발열(핫 스팟)이 적외선 열 영상 카메라에 의해 관측되었으며 브레이징 접합 결함 위치에서도 미약한 열이 관측되었다. 배경 감산 평균 및 히스토그램 평활화 처리 등의 영상처리를 통해 브레이징 접합의 결함을 확인하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권4호
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• pp.239-245
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• 2000

A copper-tungsten sintered alloy(WCu) has been friction-welded to a tough pitch copper (Cu) in order to investigate friction weldability. The maximum tensile strength of the SWu-Cu friction welded joints had cp to 96% of those of the Cu base metal under the condition of friction time 0.6sec, friction pressure 45MPa, upset pressure 125MPa and upset time 5.0sec. And it is confirmed that the tensile strength of friction welded joints are influenced highly by upset pressure rather than friction time. And it is considered that mixed layer was formed in the Cu adjacent side to the weld interface, W particles included in mixed layer induced fracture in the Cu adjacent side to the weld interface and also, thickness of mixed layer was reduced as upset pressure increase.

• Journal of Welding and Joining
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• 제11권1호
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• pp.62-72
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• 1993

Recently there is an increased interest in joining of ceramics to metals and brazing now an accepted method of joining for a wide variety of ceramic to metal combination. The present research work is aimed at establishing the basis of the metal-ceramic joining of $Al_{2}$O$_{3}$ to STS 304 with using Cu-7.5wt% Zr insert metals. Also the microstructures of the brazed joints were observed by using optical microscope and SEM and the reaction products were analyzed by using EDX, WDX and XRD. As a result, the following findings were obtained. The reaction layers of the brazed joints of $Al_{2}$O$_{3}$ to STS 304 are composed of four layers at the bonded interlayer. Double reaction layers are formed at the interface of $Al_{2}$O$_{3}$ insert metal. Layer I was composed of ZrO$_{2}$ particles, Fe-Cr-Ni compounds in Cu matrix, while layer II ZrO$_{2}$ band phase containing Fe-Cr-Ni compounds.

• Journal of Welding and Joining
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• 제31권6호
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• pp.65-70
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• 2013

In joining Alumina to copper plate by Mo-Mn metallizing process, the effects of the composition of metallizing paste on the bonding strength were investigated. The bonding strength increased with increasing Mn amount in the paste up to 20% but followed by the decrease with addition of Mn. The maximum bonding strength reached 50MPa at 20%Mn when heated to $1550^{\circ}C$ for 60minute. The addition of Si to the metallizing powder increased the bonding strength of the joint by enhancing the mechanical bonding between the Alumina and the metallizing layer due to the decrease of layer viscosity with the addition of $SiO_2$. It is thought that MnO reacted with $Al_2O_3$ to yield $MnAl_2O_4$ spinel, forming a joint.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.451-453
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• 2012

7톤급 로켓엔진 가스발생기에 대한 개념설계와 제작방법에 대해서 기술하였다. 엔진 시스템 설계의 결과로서 연소실 압력, 혼합비, 전체유량이 각각 6 MPa, 0.321, 1kg/s로 결정되었다. 이 변수들을 기본으로 가스발생기의 개념설계가 수행되었고 외형 치수는 대략 ${\Phi}100{\times}250mm$ 정도이다. 가스발생기 대부분의 부품들은 브레이징이나 TIG 용접을 통해 서로 결합되며 가능한 모든 단계에서 강도/기밀시험을 수행하여 용접 부를 점검한다.

• 소성∙가공
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• 제16권2호
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• pp.113-119
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• 2007

Rapid mold heating has been recent issue to enable the injection molding of thin-walled parts or micro/nano structures. Induction heating is an efficient way to heat material by means of an electric current that is caused to flow through the material or its container by electromagnetic induction. It has various applications such as heat treatment, brazing, welding, melting, and mold heating. The present study covers a finite element analysis of the induction heating process which can rapidly raise mold temperature. To simulate the induction heating process, the electromagnetic field analysis and transient heat transfer analysis are required collectively. In this study, a coupled analysis connecting electromagnetic analysis with heat transfer simulation is carried out. The estimated temperature changes are compared with experimental measurements for various heating conditions.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2004년도 춘계 학술발표대회 개요집
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• pp.305-307
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• 2004

One set of rotor coils is required per each large generator rotor assembly, Rotors consist of two directly opposing poles. Each pole requires from 5 to 9 coils. Each coil is made up of two halves identified on the connection end. These coil halves will be joined together by butt brazing process during subsequent rotor assembly. Each half coil is made up of typically 4 to 9 layers of copper conductors. Because of Generator rotor is rotated very high speed with 3,600RPM, the quality soundness of brazed joints is very important at each coil. But, it is very difficult to be optimized non-destructive evaluation, because c-coil has the long shape and evaluation is to be done assembled condition. In this paper introduce newly developed inspection process and acceptance standards for the ultrasonic inspection of " C" coil butt braze. This inspection system is a semi-automatic ultrasonic flaw detector with data acquisition and retention capable of assessing the relative lack of bond of brazed butt joints

• 대한기계학회논문집A
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• 제31권5호
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• pp.594-600
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• 2007

Rapid mold heating has been recent issue to enable the injection molding of thin-walled parts or micro/nano structures. Induction heating is an efficient way to heat a conductive workpiece by means of high-frequency electric current caused by electromagnetic induction. Because the induction heating is a convenient and efficient way of indirect heating, it has various applications such as heat treatment, brazing, welding, melting, and mold heating. The present study covers an experimental investigation on the rapid heating using the induction heating and rapid cooling using a vortex tube in order to eliminate an excessive cycle time increase. Experiments are performed in the case of a steel cup mold core with various heating and cooling conditions. Temperature is measured during heating and cooling time, from which appropriate mold heating and cooling conditions can be obtained.

• 한국생산제조학회지
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• 제21권6호
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• pp.926-931
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• 2012

Rotary bar was cutting tool being in use for deburring scale after welding metal and for eliminating sharp edges. It was necessary to develop exclusive 6-axis machine being possible to process machining continuously for making an cutting edge of rotary bar and to revise easily machining program. This study aimed at the structural analysis of strength according to the configuration of new made 6-axis machine and at the machining accuracy and durability of rotary bar. As a result of test, the runout of new rotary bar manufactured out of 6-axis machine was decreased from 0.385 mm to 0.027mm extensively than old one. And good cutting ability and durability was obtained equal quality compared with imported products.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.251-253
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• 2007

현재 다이아몬드 공구에서 극세선에 브레이징 공정을 이용하여 다이아몬드를 접합하는 기술은 국내외 적으로 전무한 상태이다. 이 연구는 금속 와이어에 다이아몬드를 브레이징을 실시하여 최적의 와이어 브레이징 공정법을 개발 하는데 있다. 다이아몬드와 금속필러메탈 접합 계면에서의 금속성분과 탄화물의 거동을 분석하며, 브레이징에 따른 와이어의 물성 변화를 관찰하였다. 금속필러로는 Ag-Cu-5Ti(wt.%)을 사용하였으며, 와이어는 스테인리스를 이용하였다. 브레이징 공정은 진공 접합 장치를 이용하여 $800{\sim}1000^{\circ}C$에서 유지시간 $5{\sim}30$분로 실시하였다. 브레이징된 다이아몬드는 $900{\sim}950$도, 유지시간 10분 사이에서 각각 건전한 계면과 표면을 얻을 수 있었으며, 계면에서 Ti-rich상과 화합물이 확인되었다. 또한 열처리 따른 와이어의 최적의 건전한 상태를 고찰 하였다. 다이아몬드와 Ag계 브레이징 필러의 계면에서의 미세조직 및 화학반응의 메커니즘은 SEM, EPMA, XRD를 이용하여 분석하였다.