Amorphous Metallic Fibers Research Articles

비정질 금속섬유 혼입율에 따른 모르타르의 유동성 및 경화특성

Generally, steel fiber is broadly used to improve the mechanical and flexural strength properties of concrete, however, the steel fiber have some disadvantages including high density, fiber ball and corrosion etc. Recently, a new type of amorphous metallic fiber was developed to improve some properties of normal steel fiber such as non-corrosion and flexible properties of fiber itself. In this paper, we used the amorphous metallic fiber with 30mm of length at additional ratios of 0%, 0.5%, 1.0%, 1.5%, 2.0%, 3.0% and 4.0% to estimate the properties of the mortar with amorphous metallic fiber. And the effects of contents of amorphous metallic fiber on the flow, compressive strength, flexural strength, drying shrinkage, crack reducing property and thermal conduction property of mortar were investigated. Test results indicated that using amorphous metallic fiber in mortar resulted in improvement in the flexural properties of mortar. The flexural strength of mortar with contents of Rf 4.0% amorphous metallic fiber was about 29% higher than that of the plain mortar. The drain shrinkage using amorphous metallic fiber was improved as compared to the mortar without the amorphous metallic fiber. In addition, the thermal conduction property was similar in all mortar mixtures regardless of contents of amorphous metallic fiber.

Bond stress-slip behaviour of steel reinforcing bar embedded in hybrid fiber-reinforced concrete

Experimental study was carried out to evaluate the application of metallic fibers to confine the concrete in column-beam joint. Pullout tests on cubic specimens of size 200 × 200 × 200 mm with deformed steel bar embedded for a fixed length of 5 times the diameter of tested deformed bar were performed under monotonic applied displacement at the tip of the bar (displacement controlled tests). The key variable of the experimental study was the different confining conditions; by ordinary reinforcing steel bars, and by metallic fibers. To confine the concrete by the fibers, two different types of metallic fibers were used; amorphous metallic fibers and carbon steel hooked-end fibers. The fibers were investigated both in mono and hybrid forms. The dosage of fibers in mono fiber-reinforced concrete was kept 40 kg/m3. In case of hybrid fiber-reinforced concrete, two concrete compositions were investigated: one containing 20 kg/m3 of each fiber and second containing 40 kg/m3 of each type of fiber. The pullout tests results revealed that both types of fibers contribute to ameliorate the peak bond stress and also to improve the ascending branch of the bond stress versus slip curve in terms of stiffness. Comparison of the bond stress-slip response of anchored bar in concrete confined by the ordinary reinforcing steel bars and by the metallic fibers demonstrated that the concrete confined by the fibers in hybrid form showed better performance than the concrete confined by the ordinary steel bars in terms of peak bond stress and toughness. Since the hybrid form of investigated metallic fibers realize same effect as that by ordinary steel, the congestion of steel in seismic resistant column-beam joint can be avoided by replacing some percentage of steel ratio to confine the concrete by the metallic fibers.

Shrinkage and corrosion resistance of amorphous metallic-fiber-reinforced cement composites

This study evaluated the corrosion resistance and plastic shrinkage control properties of amorphous metallic fiber used to reinforce cement composites. Amorphous metallic fibers, based on amorphous metals, are typically thin and are believed to be highly corrosion resistant. After exposing amorphous metallic fibers to five different types of degradation environments for 30, 60, and 90days, a tensile test was conducted to evaluate corrosion resistance and reduction in tensile strength. Also, a plastic shrinkage crack test of amorphous metallic-fiber-reinforced cement composite was carried out, and comparisons were made with conventional steel-, polypropylene-, and polyvinyl-alcohol-fiber-reinforced cement composites. Test results show that amorphous metallic fibers displayed higher corrosion resistance than did steel in every degradation environment, and plastic shrinkage crack control performance was excellent.

Manufacture and Industrial Application of Fe-Based Metallic Glasses

Metallic glass alloys have been considered as attractive materials due to their excellent mechanical and magnetic properties. However, commercial application of metallic glasses has been limited not only because of high production cost, but because of low market demands. A critical production cost factor was raw material since ferrous metallic glasses were made from high purity electrolytic iron. An idea to reduce the cost was to utilize the raw materials which were taken directly from molten iron and steel manufactured at the existing steel plants. Investigations have been performed to find whether metallic glasses made of molten iron and steel demonstrated appropriate mechanical and magnetic performance. Pilot scale equipments were designed to produce amorphous metallic fibers and strips continuously under the atmospheric condition. Process conditions were optimized by controlling process variables such as alloying and nozzle design, feeding temperature, speed and so on. The glass formability was tested by XRD and DSC analysis. Possibilities of application of Fe-based metallic glasses to reinforced concrete were also evaluated. It was confirmed that a small addition of metallic glass fibers in concrete increased the mechanical performance compared to that of commercial concrete reinforced with steel wires. In addition, amorphous strips were manufactured to apply them to the transformer core. It has been demonstrated that the magnetic properties were equivalent to those of commercial products.

A study on the reinforced fibrous concrete elements subjected to uniaxial tensile loading

The structural response of prisms of cross section 100×100 mm and length of 500 mm constructed with reinforced fibrous concrete and subjected to pure tensile loading has been presented in this contribution. The main focus was to study the effects of adding different metallic fibers in mono and hybrid form in the conventionally reinforced concrete on the tension stiffening and strain development. Two metallic fibers with different geometrical, mechanical and physical properties were investigated: amorphous metallic straight fibers and carbon steel hooked-end fibers. A total of four concrete mixtures: control, single fiber and hybrid fiber reinforced concretes were prepared. The fibers were investigated at content of 20 kg/m3 for single fiber reinforced concretes, and for hybrid fiber reinforced concrete, at content of 40 kg/m3. Through studying load-deformation response of composites and strain development in steel bar and concrete, it has been found that the metallic fibers improve tension stiffening effect and influence significantly the strain development. The effect of two metallic fibers on tension stiffening was seen to be different at different loading stages. On the other hand, when fibers were used in hybrid form, the behaviour of the composite was improved at all loading stages in terms of tension stiffening and resistance to cracking.