Papers by Keyword: Bend Strength

Abstract: MgO-Al2O3-SiO2 glass-ceramics containing 4.0w% alkali oxides were prepared by conven- tional melt quenching technique. The effects of heat treatment conditions on crystal types, microstructure and break strength of the glass-ceramics were studied by DSC, XRD, SEM and break strength tests. The main crystallization phases of this glass system are β-quartz (Li2-2xMgxAl2Si3O10) and β-Spodumene, no cordierite phase found. The glass-ceramics possessed a regular network-shaped microstructure feature formed by pyroxene crystals. With the increase of temperature, the β-Quartz around pyroxene crystals converted into β-spodumene and the regular network-shaped microstructure feature getting weaker and disappeared. The average break strength of the glass-ceramics containing no cordierite crystals based on MgO2-Al2O3-SiO2 system is about 150MPa, which is much high than the base glass.

Abstract: A series of silica -based ceramic cores sintered at 1150°C, 1200°C for different times were prepared, and this study compared the three-point bending strength of room temperature and 900°C with commercially available colloidal silica sols systems. Three-point bend specimens 60 × 10 × 4 mm were cast by vacuum hot pressing and tested in a special mechanical testing machine with high temperature test system of ceramics. The effect of sintering systems and colloidal silica sols on the mechanical properties of ceramic core was discussed. It could be concluded that specimens sintered at 1150°C for 5h have an obtainable maximum bending strength and those immersed in colloidal silica sols contents showed doubled bending strength in the present research.

Abstract: Mixing three different fiber composites into concrete specimens respectively, compressive strength, splitting tensile strength and flexural strength for fiber-reinforced concrete was done. The results show that the strengths of fiber reinforced concrete are improved to some extent. Due to the addition of fiber, the fiber concrete bears some of the force in tension, thus the time from the initial crack to damage is more prolonged comparing with normal concrete. Fiber concrete specimens did not get the collapse and lower intensity suddenly. Compared with normal concrete, the maximum increase of the reinforced concrete with steel fiber SQB -32 (Ⅱ) is listed, which compressive, tensile and flexural strength are increased by 30%, 40% and 24%, respectively.

Abstract: Where the self weight of the overall RC(Reinforced Concrete) or PC(Precast Concrete) floor system needs to be considered, the quantity of in-situ concrete required can be reduced by the application of polystyrene void forms to slab. In this study, flexural behaviors of void RC and PC slab with polystyrene form were evaluated to understand the effect on the self weight reduction of the slab. This paper presents experimental works and finite element analysis on the bending of the void slabs. Six specimens were tested. The main parameters of experiments were the slab types (RC and PC), the types and arrangement details of polystyrene form, and the thickness of slab. Structural behaviors of void slabs were evaluated on the basis of failure mode, load-displacement curve, and ultimate strengths. Test results indicated that nominal strengths by ACI code agreed well with experimental results. The results of analysis were compared with the results of test for estimating the validity of analysis model.

Abstract: Using carbon nanotubes (CNTs) treated with Fenton/ultra-violet (UV) as reinforcement and phenol formaldehyde resin/graphite(PF/G) composite as matrix, a new composite for bipolar plate is fabricated by hot-pressing. The effects of different molar ratios of Fe2+ and H2O2 on the surface of the CNTs, the bend strength and conductivity of the composite produced are investigated. It is found that the surface of CNTs will be purer with the decreasing of the concentration of Fe2+; that a large quantity of hydroxyl groups and few carboxyl groups can be brought on the sidewalls of CNTs when the mole match of Fe2+ and H2O2 is 1:40; that the bend strength and conductivity of the composite increase initially and then decrease with the decreasing of mole match of Fe2+ and H2O2; and that the bend strength and conductivity of the composite can reach their best values when the mole match of Fe2+ and H2O2 is 1:40, corresponding 72.5MPa and 185.6 S•cm-1, respectively.

Abstract: In this paper the influence of gypsum-water ratio, filler types and calcination temperature on gypsum bending strength were analyzed by the means of experiments. Spiral-shaped gypsum mold was made by gypsum molding material and mobility experiment was conducted on Pb-Sn alloys. Compared with pure gypsum, gypsum mixture had better mechanical properties. The fluidity of the alloy in the gypsum mold was prone to casting pressure, pouring temperature and alloy ratio. The research results have benefit to the development of gypsum casting technology.

Abstract: Transition curve is very important to bending strength and life of gear. In order to improve the bending strength of gear, the shape of three kinds of transition curve (ordinary fillet cutter tip, single circle arc cutter tip and double circle arc cutter tip) was analyzed respectively, the relationship of double circle arc cutter tip parameters was established, the relation model of sensitive part of gear and stress concentration factor ( J and γ) was determined, the effect of different transition curves of gear on bending strength ( ) was explored. The results of analysis show that the bending strength of gear cut by double circle arc cutter tip increases by 10% comparing with that of gear cut by ordinary fillet cutter tip. It provides theories foundation for the design of high bending strength gear.

Abstract: Brick- and tile manufacturing is one of the most rapidly developing industries. Professionals are constantly seeking modern technological solutions with which much better and longer lifetime of ceramic roof tiles can be reached. The aim of this R&D work was to optimize the mixing ratio of two different clay minerals of the industrial partner. The Authors have tried to develop a mixture by increasing the mixing ratio of the clay „Jamina”, which reaches or exceeds the mechanical strength and frost-resistance of the ceramic roof tiles which were made according to the present recipe used by the industrial partner. After XRD tests in virtue of preliminary mixture design, the Authors have made clay mineral mixtures that were milled and homogenized in an edge mill for an appropriate grain size. After mixing and homogenizing, samples with different length were made for further investigations with the use of a laboratory vacuum extrusion system. Shrinkage after drying and firing, apparent porosity and water absorption were measured on these samples. Mechanical test were also executed, as well as bending strength tests and compressive strength tests. On the basis of the results of the executed tests, it can be seen that the Authors were successfully developed clay mixtures, with which ceramic roof tiles can be produced with properties that are more favourable than the present mixture used by the industrial partner. The increase of the ratio of ‘Csaba I.’ clay increases the bending and compressive strength of the fired ceramic roof tiles. So the reduction of the amount of clay „Jamina” affects the mechanical properties of the ceramic roof tiles favourably.

Abstract: AlON/SiC composites were synthesized by hot-pressing sintering technology using SiC and prepared AlON powder as raw materials. The influence of SiC content on relative density, hardness, bend strength and microstructure of multiphase material was studied by several testing methods, such as XRD and SEM. The strengthening mechanism of SiC was also explored in this paper. The experimental results indicated that with the addition of SiC, the bend strength of the multiphase material was obviously enhanced, comparing with AlON single phase material, and ultimately it reached 310 MPa. The best adding mass content of SiC was 8% and its strengthening mechanism was mainly thermal expansion mismatch and fine grain strengthening. As the adding mass content of SiC increased, the hardness of AlON/SiC ceramic matrix composite was increased gradually, the bend strength firstly increased and then decreased, and the main fracture way of composite was changed from intergranular fracture to transgranular fracture and finally both of the two modes of fracture occurred. This research had positive significance on deep popularization and application of AlON ceramic material.

Abstract: Rod-like submicron Al2O3 powder was prepared by the controllable hydrolyzation of aluminium isopropoxide in streams atmosphere. XRD data show the rod-like Al2O3 has a γ- Al2O3 structure. TEM images display the length of the submicron Al2O3 is in the range of 100-300 nm and the slenderness ratio is above 10. The rod-like Al2O3 powder was added into the submicron Al2O3 (D50 = 0.5 μm, purity > 99.99%) to increase the bending strength of the sintered body and to decrease the sintering temperature. SEM images display that the Al2O3 sintered at 1450 °C with rod-like Al2O3 added has a higher density than the virgin Al2O3 and the Al2O3 grains have the trans-crystalline fracture. The bending strength of the sintered Al2O3 with 5 wt% rod-like Al2O3 added is 205 MPa, which increases 241%. A sharp shrinkage in 1300-1400 °C appeared in the sintering shrinkage curves characterized by DIL show the rod-like Al2O3 also acts as the sintering aid.