Tribological and aging behavior of hybrid Al 7075 composite reinforced with B4C, SiC, and TiB2

In this study, B4C+SiC/B4C +TiB2/SiC+TiB2 hybrid reinforcements were added to Al 7075 matrix via the powder metallurgy method. The powders were subjected to mechanical grinding for 240 min, as shown in the graphical abstract. The hybrid composite powder structure produced by the mechanical grinding was then placed in a vertical casting chamber and molten Al 7075 (main matrix) was added to obtain the samples. Samples were dissolved for 1 h at 480 ?C, and then aged at 120 ?C in 4-h increments (32 h in total). After the aging process, the wear behavior of the samples was investigated. In the study, FESEM images were examined for microstructural analysis, and hardness plots of the aged samples were created depending on the time after the solutioning treatment. The friction coefficient, volume loss, and worn surface images were investigated to determine the wear behavior of the hybrid structures. Results showed that the increased reinforcement rate and the reinforcement size and type directly affected the hardness and wear behavior. In the experiments, the highest hardness and wear resistance behavior were obtained in the hybrid sample of 3% B4C + 3% SiC after 12 h of aging.

Optimising Computational Fluid Dynamic Conditions for Simulating Copper Vertical Casting

A 2-D finite volume Computational Fluid Dynamic (CFD) model, using Ansys Fluent vR.1 of a vertically oriented upwards continuous casting (VUCC), was investigated for 8 mm, oxygen free copper (OFCu). The simulations enabled the mapping of the cast OFCu solidification front (SF) interface from liquid to solid. Optimisation of the simulation parameters were investigated which included mesh size and the Ansys specific ‘mushy zone’ constant (Amush), which is used to account for fluid flow dampening at SF within the model. Observations of the SF, the change in fluid volume in the die, the simulation convergence and the total simulation time, revealed that the optimised casting parameters were for mesh size 1×10-4 m and Amush 106 kg/m3s. These parameters were compared with the cast rod and highlighted qualitatively the relationship between grain growth direction and SF position during a casting pulse cycle.

Effect of Placement Method on Projectile Impact Resistance of UHPFRC

This paper presents the results of an experimental investigation of the impact resistance of UHPFRC slabs. The influence of horizontal and vertical casting of thin slabs against penetration by a projectile is described. The resistance of penetration by a projectile was investigated using projectile with lead core. The results indicate different penetration depths and crater diameters in the target specimens for both kind of casting. Which points on a different arrangement of fibers for horizontal and vertical casting slabs. However, the protective ability is guaranteed in both placement method. Based on the present findings the slabs from ultra-high performance fiber-reinforced concrete casted vertically appear to be most efficient in protection against projectile impact.

Thermodynamic of Moving Mould in Anode Plate Vertical Casting Device

Machinery, especially, lead electrolysis Non-ferrous Metallurgy industry needs higher and higher temperature accuracy in manufacturing equipments by accompanying the development of the science and technology. During the process of lead electrolysis manufacturing equipment, the anode plate vertical casting system is a producing device which aims to complete the casting of the anode plate. However, simple cool system and poor cool effect and lower production efficiency of the domestic anode plate manufacturing equipment are the common short comings which exist currently. Therefore, we designed in Solidworks based on a comprehensive analysis of the mechanical structure of the mold, and obtain the time of right temperature of moving mould in a stable state, thought to verify the rationality of the design of the equipment cooling system.

Exploration of Rotation Lowering with Building RC Box-Rib Arch Bridge

Arch rib construction of Zhenzhu Bridge on the road from Wuchuan to Pengshui in Guizhou uses construction technology of vertical casting in the first place, and then vertical rotation, and the total weight of which is 610t. This paper introduces technical points and process of vertical rotation construction, and has made beneficial exploration and summary of such kind of construction technology.OverviewBridge rotation construction has advantages including saving costs for hoisting and erecting frames, reducing risks of frames losing stability when casting arch rib concrete, convenient, flexible, safe, reliable and good integrated construction operation, structural line type and internal forces are easy to adjust and control, small range requirement of construction site, and low impact on surrounding environment. Bridge rotation construction would have a broad application prospect in the practice of bridge construction, especially in Chinas southwest area with wide distribution of deep groove and dangerous gully, such construction method is more advantageous. Therefore, practice and research on such construction technology are very practical and significant.Ordinary vertical rotation construction is to have low casting or arch rib assembling, and then lift upward to reach the designed location. Concrete arch rib construction of Zhenzhu Bridge on the road from Wuchuan to Pengshui in Guizhou uses the technology of negative-angle vertical rotation construction, vertical casting arch rib, and then lowering rotation with weight of 610t. Such construction technology is used in China for the first time, while current vertical rotation of the same type of RC arch rib in China has the maximum weight. Based on emphasis on introducing construction technology characteristics of this bridge, this paper also includes innovation and beneficial exploration on the new construction technology of negative-angle vertical rotation.

The Effects of Plates Position in Vertical Casting Producing Thin Wall Ductile Iron

In the general rule of casting design the thickest part of the cast should be placed near to the ingate. This arrangement was meant to guarantee the completion of filling process. An unusual vertical casting design to produce plates with different thicknesses was established based on the idea that the heat from molten metal will always warm up its entire runner. In this design the thinnest plate is placed near to the ingate. The design was made for producing thin wall ductile iron. This research was conducted to see the effects of reverse thickness arrangement in casting design to the microstructure and mechanical properties of the plates. Plates produced by this design were compared to plates produced by the same design with general casting arrangement. Thicknesses of the plates produced in this casting were 1, 2, 3, 4, and 5 mm. The moulds used were made from furan sand. Beside experiment, casting design simulation with Z-Cast was also conducted to ensure the completion of filling process and to see the manner of solidification. Casting simulation showed that arrangement of plates gave different filling and solidification manners. Although there were some differences, the filling was successful for both arrangements of plates. Skin effect was found in both designs. Nodule counts and nodularity were higher in the new design while average nodule diameters were lower. The result gained in tensile and hardness test did not follow the correlations in the characteristic of graphite. Mechanical properties showed that position of plate, ignoring the thickness, influence tensile strength and hardness.