Atomic Diffusion and Crystal Structure Evolution at the Fe-Ti Interface: Molecular Dynamics Simulations

The diffusion bonding method is one of the most essential manufacturing technologies for Ti-steel composite plates. In this paper, the atomic diffusion behavior at the Fe-Ti interface during the bonding process of Ti-steel composite plates is studied using classical diffusion theory and molecular dynamics (MD) simulation. Henceforth, the diffusion mechanism of Fe and Ti atoms at the bonding interface is obtained at the atomic scale. The results show that Fe and Ti atoms diffused deeply into each other during the diffusion process. This behavior consequently increased the thickness of the diffusion layer. Moreover, the diffusion quantity of Fe atoms to the Ti side was much greater than that of Ti atoms to the Fe side. Large plastic deformation and shear strain occurred at the diffusion interface during diffusion. The crystal structure of the diffusion zone was damaged and defects were generated, which was beneficial to the diffusion behavior of the interface atoms. As the diffusion time and temperature increased, the shear strain of the atoms at the interface also increased. Furthermore, there is a relationship between the mutual diffusion coefficient and the temperature. Subsequently, after the diffusion temperature was raised, the mutual diffusion coefficient and atomic disorder (Fe atom and Ti atom) increased accordingly

Effect of Particle Size on the Thermal Shock Resistance of Plasma-Sprayed YSZ Coatings

In this study, yttria-stabilized zirconia (YSZ) coatings were deposited by atmospheric plasma spraying (APS) using feedstocks with two different particle sizes. The effect of particle size on the pore structure and failure mechanism of the coatings was investigated. The evolution of the pore structure of the two kinds of coatings during cyclic thermal shock test was described by quantitative metallography. The influence of pore orientation on the thermal stress of the coating system was analyzed by the finite element method. It was found that the coatings deposited using coarse particles show a high thermal shock life time. The orientation of the pores in the coatings prepared by different particle sizes was different. A structural parameter was proposed to effectively characterize the pore orientation of the coatings. Coatings prepared by coarse YSZ powder tend to form almost the same number of horizontal and vertical pores, while coatings prepared by fine powder tend to form horizontal ones parallel to the direction of the substrate. The simulation results revealed that the vertical pores can reduce the thermal stress in the coating. The results of this investigation are a benefit to the design and integrity of TBCs

Contribution of Fertilizer, Density and Row Spacing Practices for Maize Yield and Efficiency Enhancement in Northeast China

The research aimed to assess the contribution of fertilizer, density, and row spacing in integrated cultivation measures and identify their regulation mechanism on canopy architecture and factors in biomass accumulation in spring maize. Zhengdan 958 was used as the experimental material, and the optimum mode (OM) was identified based on a preliminary experiment, including the optimal fertilizer management, suitable plant density and wide-narrow row spacing, and dramatic yield performance (11,445.16 kg ha−1 in 2017). Then, the effects of these practices on maize canopy structure performance were analyzed using the omission factors design experiment in optimum mode (OM). Treatments were set as follows: without fertilization (OM-F), without density (OM-D), and without wide-narrow plant spacing (OM-S). The results showed that the contribution of fertilization was maximum (23.85%), the second was intensive planting (16.05%), which promoted nitrogen accumulation and transport in leaves and stems via increased leaf area index and dry matter accumulation around the anthesis simultaneously, elevating the radiation utilization efficiency of the canopy and allowing a higher grain weight to be obtained. Wide-narrow row spacing yield contribution is minimum among the measures (8.649%), which could regulate the leaf and radiation transmittance in the middle and bottom layer of the canopy, while increasing the nitrogen accumulation of leaves and stalks in the silking stage, then significantly enhance the nitrogen transport and the matter accumulation of maize after anthesis. Our results showed that fertilizer management and density were the essential practices for integrated cultivation mode for northeast China. Moreover, wide-narrow row planting was advocated if permitted, which could elevate the utilization efficiency of radiation to 1%, and the yield of more than 11,000 kg ha−1 was obtained in Northeast China

Peanut Shell Biochar’s Effect on Soil Physicochemical Properties and Salt Concentration in Highly Saline-Sodic Paddy Fields in Northeast China

Soil salinization is a major ecological threat to crop growth and production. Biochar addition can alleviate the negative impacts of saline-sodic stress in crops. Here, a two-year field experiment was conducted in a highly saline-sodic paddy field to evaluate the response of soil physico-chemical properties, ionic concentration, and rice yield to biochar applications. The soil was amended with peanut shell biochar as follows: zero biochar (B0), 33.75 t ha−1 (B1), 67.5 t ha−1 (B2), and 101.25 t ha−1 (B3). Biochar significantly reduced soil bulk density (BD), while it markedly increased total porosity (TP) and saturated hydraulic conductivity (Ks). Furthermore, biochar markedly decreased the Na+ concentration, Na+/K+ ratio, Na+/Ca2+ ratio, HCO3-, and CO32- while it increased the concentrations of K+, Ca2+, and Mg2+. Biochar significantly decreased the electrical conductivity of soil saturation extract (ECe). The exchangeable sodium percentage (ESP) of B1, B2, and B3 were 53.6%, 62.3%, and 71.0% lower, respectively, than that of B0, and the corresponding decrease in sodium adsorption ratio (SARe) was 51.2%, 58.1%, and 60.5%. Biochar had no effect on the soil pH but significantly increased the soil cation exchange capacity (CEC). The rice biomass yield, grain yield, and harvest index significantly increased after biochar application