분사주조에 의한 입자강화 금속기지 복합재료의 제조시 액적의 열적거동과 미세조직에 대한 고찰

김명호,배차헌,정해용,박흥일 ( Myung Ho Kim,Cha Hurn Bae,Hae Young Jeong,Heung Il Park ) 한국주조공학회 1992 한국주조공학회지 Vol.12 No.4

N/A Particle-reinforced metal matrix composites via the Osprey spray casting process were fabricated by injecting second phase particles of Al₂O₃(<40㎛) and W(6㎛) into the spray of Cu droplets, and the thermal behaviors of the composite droplets during flight were considered theoretically on the basis of mixing modes between the Cu droplets and the reinforced particulates injected. It was found that the W-injected spray is comprised of particle-embedded droplets, and the Al₂O₃-injected spray comprises particle-attached droplets. From the predicted results of the thermal behaviors of the composite droplets and preforms produced, it is concluded that the thermal behaviors of the composite droplets during flight, and during the subsequent deposition are strongly influenced by its mixing modes between the reinforced particulates and Cu droplets during flight.

THE EFFECTS OF ALLOYING ELEMENTS AND COOLING RATES DURING SOLIDIFICATION ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF P-CONTAINED C/V GRAPHITE CAST IRONS

김명호,박흥일,김우열,배차헌 ( Myung Ho Kim,Heung Il Park,Woo Yeol Kim,Cha Hurn Bae ) 한국주조공학회 1995 한국주조공학회지 Vol.15 No.6

N/A This study was undertaken to obtain an improved understanding of the effects of alloying elements on the residual amounts of Mg in the melt and on the resultant microstructure of compacted vermicular graphite cast irons, and the influence of alloying elements and cooling rates during solidification on the formation of phosphide eutectics, and on the mechanical properties of compacted vermicular graphite cast irons containing copper, tin, molybdenum for producing pearlitic matrix, and also containing phosphorus and boron for increasing wear resistance were evaluated.

내마모 CV 흑연주철의 공정인화물 형성에 미치는 합금원소 및 냉각속도의 영향

박흥일,김명호 ( Heung Il Park,Myung Ho Kim ) 한국주조공학회 1989 한국주조공학회지 Vol.9 No.4

N/A The effects of the alloying elements and cooling rates on the formation of phosphide eutectics of compacted vermicular graphite cast irons containing copper, tin, molybdenum for producing pearlitic matrix, and also containing phosphorus and boron for increasing wear resistance, were investigated. The liquidus phosphide eutectic was found to solidify as a pseudo-binary phosphide eutectic, but with increasing of the cooling rate non-equlibrium phosphide eutectic with needle type carbide could be formed. However, the liquidus phosphide eutectic containing both phosphorus and carbideforming boron was found to solidify always as a non-equilibrium phosphide eutectic with coarse carbide, independent from the cooling rate. It was also confirmed that the tiny isolated phase observed by SEM was gamma iron solid solution with phosphorus, silicon, molybdenum and the matrix containing these tiny islands was phosphde phase, containing manganese and molybdenum. The addition of copper was found to decrease the tendency of forming ledeburitic carbides in the phosphide eutectic.

C/V 흑연주철의 미세조직에 미치는 Cu 첨가의 영향

박흥일,김명호 ( Heung Il Park,Myung Ho Kim ) 한국주조공학회 1986 한국주조공학회지 Vol.6 No.4

The effects of copper as an alloying element on the microstructure of Compacted Vermicular graphite cast iron which was treated with Mg-REM spheroidizer have been studied. With the increase of copper content up to 2.0wt%, the following results were obtained; First, the ratio of residual magnesium content in the as-cast iron has been found to be increased, possibly due to the decrease of sulfur content in the melt. Thus, the morphology of graphite in the as-cast iron has been found to be more nodular type. Second, the proportion of pearlite in the matrix has been found to he increased, however the matrix being with free carbide precipitates in the copper range of 1.2wt.% to 2.0wt.%. Third, the tensile strength of the as-cast iron in the temperature up to 400℃ was increased.

CV 흑연생성에 미치는 인 (P) 및 보론 (B) 첨가의 영향

박흥일,김명호,김영홍 ( Heung Il Park,Myung Ho Kim,Young Hong Kim ) 한국주조공학회 1989 한국주조공학회지 Vol.9 No.5

N/A The effects of phosphorus and boron additions and isothermal holding time on the residual magnesium and sulfur content, and on the resultant graphite structure of cast irons were investigated. The effective recovery ratio of magnesium showed that adding phosphorus to the melt retarded the fading rate of magnesium but adding boron accelerated it. However, the residual sulfur content was found to be decreased with isothermal holding time at the beginning, and then to be increased again with holding time by resulfurization. The Mg-Equivalent for producing compacted vermicular graphite structure was found to be increased with the addition of phosphorus, whereas to be decreased with the addition of boron.

용탕단조한 미세강선 보강 알루미늄 복합재료의 미세조직에 대한 고찰

정봉용,이인우,박흥일,김준수,김명호 ( Bong Yong Jeong,In Woo Lee,Heung Il Park,Jun Su Kim,Myung Ho Kim ) 한국주조공학회 1994 한국주조공학회지 Vol.14 No.5

N/A Aluminum matrix composites reinforced by fine steel wires were fabricated by squeeze casting process. Preforms made of fine steel wires were prepared with different surface conditions, namely uncoated(TN), carbo-nitriding treated(TT), and brass coated(TA). Squeeze casting were performed under the pressure of 1500㎏/㎠ for 3min. during solidification, and pouring temp. of the melt being 750℃ and the steel mold being preheated at 250℃. Microstructural characteristics were evaluated, particularly concerned with the effect of the surface conditions of the preforms. The results obtained from this study are like these. TN specimens show partially non-wetted regions, due to easy formation of oxides on the surface of the fine steel wires. TT specimens show no interfacial reaction between the steel wires and the aluminum alloy matrix, possibly due to the formation of carbo-nitrided zone on the surface of the steel wires. TA specimens show excellent wettabillity between the reinforced steel wires and the aluminum alloy matrix and very thin interfacial zone is formed between them. During the solution hardening treatment of TA specimens, thickness of the interfacial reaction zones were increased with the solution treating time. TA specimens show typical ductile fracture in tensile test, but TT specimens show brittle fracture possibly due to the formation of the brittle hard surface on the steel wires during carbo-nitriding treatments. TA specimens which were reinforced with 40 vol.% of the fine steel wires exhibit high tensile strength of 77.l㎏f/㎟ and impact value of 8.l㎏f-m/㎠.

내마모 CV 흑연주철의 합금설계

박흥일,김우열,배차헌,김명호 ( Heung Il Park,Woo Yeol Kim,Cha Hurn Bae,Myung Ho Kim ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.4

N/A The effects of alloying elements on the structure and mechanical properties of compacted/vermicular graphite cast irons containing copper, tin and molubdenum for producing pearlite matrix, and also containing phosphorus and boron for increasing wear resistance, were investigated. The Brinell hardness and ultimate tensile strength of the specimens with the range of compositions, [1.5% Cu-0.05% Sn-(0.2-0.4)% Mo-(0.2-0.6)% P-(0.035-0.070)% B], was found to fall within in the following range, depending on their composition; Brinell hardness of BHN 250-315, ultimate tensile strength of 28.1-40.3㎏/㎟. It was also found within this experiment that CV graphite cast irons possessing higher amount of phosphide eutectic exhibit better wear resistance, but the wear resistance became deteriorate when the area fraction of phosphide eutectics exceed more than 10%. From these experimental results, it could be concluded that the CV graphite cast iron containing 1.5% Cu, 0.05% Sn, 0.4% Mo, 0.2% P and 0.035% B showed good mechanical and wear resistance properties.

CV 黑鉛鑄鐵의 製造에 관한 基礎硏究

朴興日,金明鎬 울산대학교 1984 연구논문집 Vol.15 No.2

본 연구에서는 구상흑연주철용 용탕보다 S 및 Mn의 함량이 다소 높은 灰鑄鐵用 熔湯(GC-10規格)을 사용하여 黑鉛球狀化劑의 少量첨가법에 의한 CV黑鉛鑄鐵을 제조하는데 필요한 基礎資料를 얻고자 시도하였다. 특히 본 연구에서는 흑연구상화제의 첨가량에 따른 잔류화학성분의 변화 및 흑연조직의 변화에 관하여 중점적으로 고찰하였다. 그 결과 Mg回收率은 Fe-Si-Mg첨가량이 적을수록 높으며, CV黑鉛組織은 Mg當量/S의 값에 따란 변화하며 fading 효과는 CV黑鉛鑄鐵의 경우가 구상흑연주철의 경우보다 매우 완만함을 알 수 있었다. A method for the production of Compacted-Vermicular graphite cast iron with GC-10 melt by means of additions of Ge-Si-Mg alloy gas been studied. The variations of both the residual alloying compositions and the structure of as-cast iron with the amount of Fe-Si-Mg additive have been investigated, and following results were obtained; the ratio of residual Mg content in the as-cast iron to the initial amount of additive has been decreased with increasing amount of Fe-Si-Mg additive. The graphite structure of the as-cast iron gas been found to vary with the ratio of Mg equbalent/S, and fading phenomena with holding time in Compacted-Vermicular graphite cast iron has been found to occur more slowly than in spheroidal graphite cast iron.

급속응고된 Al-Zr 합금의 시효현상에 미치는 Si첨가의 영향

최상욱,박홍일,김명호 울산대학교 1987 연구논문집 Vol.18 No.2

본 연구에서는 급속응고된 Al-Zr 합금의 과포화 고용도에 미치는 제3첨가 원소 Si의 영향 및 급속응고된 Al-Zr-Si 합금계의 시효특성에 관하여 실험적으로 조사하였다. Twin-roller 장치에 의하여 급속응고시킨 시편의 응고속도는 10?? K/s 정도였으며, 이때 Al기지내에 Zr은 약 1 wt.% 정도만이 과포화 고용되었다. 그러나 Si의 첨가량이 증가됨에 따라 Zr의 과포화 고용도는 증대되어 Si의 첨가량이 1 wt.% 일때 Zr은 1.7 wt.% 정도 Al기지내에 완전 과포화 고용되었다. 그리고 Si의 첨가량이 증가됨에 따라 Al-Zr 합금의 미소경도는 증대되었다. Al -1.7wt.%Zr -1.0wt.%Si 합금을 시효처리하면 Si이 우선 미세한 구상석출물을 형성하며 초기 시효경화를 일으킨 후, 잇따라 Zr의 준안정 석출물이 불연속 석출되어 성장하며 최대 시효경화를 나타냄을 알 수 있었다. An experimental investigation has been made about the effects of the third alloying element silicon on the sold solubility of zirconium in the aluminium, and on the ageing phenomena of Al-Zr-Si alloys. Rapidly solidified specimens were prepared by a twin-roller quenching apparatus in the form of long, thin ribbon, whose cooling rate was estimated to be about 10?? K/s. Under such a cooling rate, the maximum solubility of zirconium in solid aluminum was extended to about 1.0wt.%. However, it was extended up to 1.7wt.% by addition of 1.0wt.% silicon. With the increase of silicon content, the microhardness of Al-Zr alloys were increased as well. Ageing of supersaturated Al-1.7wt.% Zr-1.0wt.% Si solid solution appeared to occur in three sequential stages; Ⅰ. precipitation of silicon as fine spherical particles which harden the alloys, followed by Ⅱ. discontinuous precipitation of metastable zirconium phases which produce remarkable age hardening of the alloys, and finally Ⅲ. formation of coarse equilibrium zirconium phases.