키토산 필름은 농업, 식품과 제약 분야에서 응용이 가능하다. 그러나 키토산으로만 만들어진 필름은 기체투과성이 높고 기계적 물성에 약하다. 따라서 본 연구에서는 기체 투과성을 낮추고 기계적 물성을 높이기 위해 층상구조를 갖는 점토광물의 일종인 montorillonite (MMT)와 양이온 생체고분자인 키토산을 이용하여 양이온 교환과 수소결합과정을 통해 Na+-MMT에 키토산을 삽입하여 키토산/Clay 나노복합재료를 제조하였다. 키토산/clay 나노 복합재료의 X-ray 회절패턴에서 2θ=7.5º에서 MMT의 basal reflection이 나타났고, 2θ=3~5º 주위에서의 새로운 약하고 넓은 peak로서 더 낮은 각에서 MMT의 basal reflection의 이동에 의해 삽입된 나노 구조의 형성을 증명하였다. 또한 TGA thermogram를 이용하여 clay의 함유량이 증가할수록 제조된 나노복합재료의 열분해가 일어나는 범위의 질량감소가 줄어드는 것을 확인하므로서 내열성을 관찰하였다. 기계적 물성 성질을 측정하여 clay 함유량의 증가에 따른 인장 강도와 인장 모듈러스의 변화를 관찰하고, 키토산이 층상 실리케이트 내에 삽입하여 제조된 나노복합재료에서 clay의 함유량이 증가할수록 질소 투과경로의 tortuosity를 증가시켜서 기체 투과도를 감소시키는 것도 확인하였다.

The microstructure and mechanical property of hot-pressed composites with a different temperature for atmosphere changing from H to Ar have been studied. When atmosphere-changed from H to Ar gas at 145, the hot-pressed composite was characterized by inhomogeneous microstructure and low fracture strength. On the contrary, when atmosphere-changed at low temperature of 110 the composite showed more homogeneous microstructure, higher fracture strength and smaller deviation in strength. Based on the thermodynamic consideration and microstructural analysis, it was interpreted that the Cu wetting behavior relating to the formation of CuAlO is probably responsible for strong dependence of microstructure on atmosphere changing temperature. The reason for a strong sensitivity of fracture strength and especially of its deviation to atmosphere changing temperature was explained by the microstructural inhomogeneity and by the role of CuAlO phase on the interfacial bonding strength.

Plastic deformation was observed by TEM around the intragranular SiC particles in the matrix for nanocomposite system. The dislocations are generated at selected planes and there is a tendency for the dislocations to form a subgrain boundary structure with low-angel grain boundaries and networks. In this study, dislocation generated in the matrix during cooling down from sintering temperatures by the highly localized thermal stresses within and/or around SiC particles caused from the thermal expansion mismatch between matrix and SiC particle was observed. In monolithic and microcomposite system. These phenomena is closely related to the plastic relaxation of the elastic stress and strain energy associated with both thermal misfitting inclusions and creep behaviors. The plastic relaxation behavior was explained by combination of yield stress and internal stress.

Processing and properties of composites with Ni-Fe content of 10 and 15 wt% were investigated. Homogeneous powder mixtures of /Ni-Fe alloy were prepared by the solution-chemistry route using , and powders. Microstructural observation of composite powder revealed that Ni-Fe alloy particles with a size of 20nm were homogeneously dispersed on powder surfaces. Hot-pressed composites showed enhanced fracture toughness and magnetic response. The properties are discussed based on the observed microstructural characteristics

다발체 형성과 인발 공정으로 제조된 Cu-Nb 필라멘트 미세복합재료의 기계적 전기적 특성에 대하여 연구하였다. Nb의 함량이 증가함에 따라 강도는 점차 증가하였으나 연성은 Nb의 함량에 무관하였다. 293K와 75K에서의 항복강도의 비율은 Cu-Nb 미세복합재료의 Young의 계수 비율과 비슷하게 관찰되었다. 이러한 사실은 주로 장범위 방해물(athermal obstacles)들이 Cu-Nb 마세복합재료의 강도에 영향을 미친다는 것을 의미한다. 파면 조직관찰 결과는 Cu-Nb 미세복합재료는 Nb의 함량에 판관계없이 연성파괴의 특성을 나타내었으며, 부전선재 (subelematal wires)사이의 계면을 따라 발생하는 2차크랙 (secondary crack) 의 양은 Nb 함량이 증가함에 따라 증가하였다. 전기 전도도와 비저항비 (ρ293k/rho75k)는 Nb 함량이 증가할수록 감소하였다. 이와 같은 Nb함량에 따른 전기전도도와 비저항비의 감소는 계면산란의 기여도가 증가하였기 때문이다.

An optimum route to fabricate the nanocomposites with sound microstructure and improved mechanical properties was investigated. Microstructural investigations for the composites prepared using -nitrate showed that fine Cu particles with average size of 150 nm were homogeneously distributed within the matrix grains and at the grain boundaries. Fracture strength of 953 MPa and toughness of 4.8 Mpa(equation omitted)m were measured for the composite. The strengthening and toughening of the composites are explained by the refinement of the microstructure and the crack bridging/deflection, respectively.

In this study, the fabrication of /5vol.%Cu nanocomposite and its mechanical property were discussed. The nanocomposite powders were produced by high energy ball milling of and Cu elemental powders. The ball-milled powders were sintered with Pulse Electric Current Sintering (PECS) facility. The relative densities of specimens sintered at and after soaking process at were 96% and over 97%, respectively. The sintered microstructures were composed of matrix and the nano-sized Cu particles distributed on grain boundaries of matrix. The nanocomposite exhibited the enhanced fracture toughness compared with general monolithic . The toughness increase was explained by the crack deflection and bridging by dispersed Cu particles.