The present study evaluate the catalysis of Nd2O3 on the boriding of AISI 1045 steel using a 5% Nd2O3-containing boriding agent in a temperature range of 1 213 K to 1 350 K for 2 h-5 h. The morphology and types of borides formed on the steel surface were confirmed by optical microstructure, scanning electron microscopy and X-ray diffraction. The results show that the Nd2O3 has contrary effects on boriding process, i.e. promotion at high temperatures or hindrance at low temperatures. Nd2O3 addition can significantly reduce the activation energy of boride growth at high temperatures, decreased it from 198 kJ/mol to 137 kJ/mol, reduced by 31% in the high temperature range of 1 133 K-1 213 K as compared with that without Nd2O3 addition. The catalysis mechanism of RE element Nd during boriding process was discussed through the analysis of chemical reactions probably occurred in boriding agent, changes in surface morphology and chemical composition.
The paper studies that temperature and different interlayer contact conditions between ultra-thin wearing course and original pavement have an impact on interlayer shear stress. Calculate parameters of each layer asphalt mixture materials under different temperature through empirical formula. Substitute the parameters into BISAR3.0 software to calculate maximum interlayer shearing stress of ultra-thin wearing course under different temperature and interlayer contact conditions. The results show that interlayer contact conditions and temperature have a great influence on interlayer shearing stress of ultra-thin wearing course.
The paper uses a new energy-saving and environment-protecting road material. On the basis of comparative analysis with the road all performance of hot mix asphalt SBS modified asphalt mixture, focuses on the compaction property at the new material lower construction temperature. The results show that the energy-saving and environment-protecting road material can effectively guarantee the performance of asphalt mixture and asphalt pavement after construction temperature is lower 30°C, forming a stable compaction interval and extend the construction time. Also can reduce the emissions of harmful gases on asphalt mixing and construction process, to save energy and protect environment.
By adding Sasobit, DAT and BLT additives to reach the purpose of hot mix asphalt mixture construction temperature decreasing, achieve energy conservation and environmental protection. With an AC-13 SBS modified hot mix asphalt as reference, the high and low temperature performance and water stability of three energy-saving and environment-protecting road materials are evaluated through laboratory tests. The results show that compared with HMA, all the three kinds of energy-saving and environment-protecting road materials exhibited a significant increase by 8%-15% in high temperature stability. While the low temperature cracking resistance and anti-water damage performance of Sasobit mixture were decreased somewhat, little changes in these two aspects of the performance of the other two materials. Finally, analyses the economic benefits, and provide the basis for the choice of asphalt mixture cooling additives.
Asphalt mixing plant cold recycled materials as the layer below has been widely applied in recent years, It has better performance compared with other structural materials for the prevention and treatment of reflective cracking,for further analysis the stress conditions of the material as a grass-roots-bit suffered upper load transfer.In this paper, useing the ABAQUS software modeling analysis of three different structural pavement layers on top and bottom of the situation by force. The results show that the grassroots cold recycling layer structure has obvious characteristics of flexible it has better controlable to reflective cracking.
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