Tribological behaviors of graphene oxide partly substituted with nano-SiO_(2) as lubricant additives in water for magnesium alloy/steel interfaces

Although graphene oxide(GO)has emerged as an excellent lubricant additive in water,there remain great challenges in their practical application due to high production costs.By taking into account the low cost and also its excellent tribological properties,it is likely that nano-SiO_(2)can be used as a lubricant additive to partially replace GO.Hence,this paper aims to explore the tribological properties of nano-SiO_(2)incorporated in GO nanofluids for partial GO replacement by investigating the friction coefficient and wear volume of the prepared SiO_(2)/GO hybrid nanofluids for magnesium alloy/steel sliding pairs.The experiments reveal that the SiO_(2)/GO hybrids retain low friction coefficients as compared to individual GO or SiO_(2)at all test conditions in this study.However,as for the bearing capacity test,all samples can provide a low wear volume under the loads of 1 and 3 N.With the increase of the normal load,there is considerable differences in the anti-wear behavior.Compared with that of individual GO nanofluids,the wear volume of the GO/SiO_(2)(mass ratio of 0.3:0.2)hybrid nanofluids was reduced by50.5%at 5 N and by 49.2%at 8 N.Furthermore,the wear volume of the GO/SiO_(2)(mass ratio of 0.3:0.2)hybrid nanofluids was reduced by46.3%under the rigorous conditions,as compared to individual GO nanofluids.The findings provide new insights into developing carbon nanomaterial-based hybrid nanofluids for magnesium alloy formation.

Monthly Changes in the Resin Yield of Semi-sib Families of Pinus elliottii

Monthly changes in the resin yield of semi-sib families of Pinus elliottii during 2013-2015 were studied.The results showed that from April to October,the resin yield of the P.elliottii families was the lowest in April and the highest in July.There were significant differences between various families in terms of resin yield.The change of resin yield was closely related to temperature,and the higher the temperature was,the higher the resin yield was.P.elliottii mainly produced resin from June to September.

Heritability Analysis of Growth Traits and Selection of Semi-sib Families of Pinus elliottii

Growth traits of semi-sib families of Pinus elliottii were studied.The results showed that there were extremely significant differences between the P.elliottii families in terms of tree height,DBH and volume( P < 0.01),and the families could be selected effectively.Both family heritability and single plant heritability of growth traits of P.elliottii were high.The family heritability of tree height,DBH and volume was 0.799,0.779 and 0.770 respectively,and their single plant heritability was 0.683,0.829 and 0.742 respectively.Among them,the family heritability of tree height was the highest,while the single plant heritability of DBH was the highest.The Duncan analysis of growth traits of the P.elliottii families revealed that families 12,7,15,4 and 6 were superior families and can be used as high-yield families.

CuO-modified activated carbon for the improvement of toluene removal in air

We used an impregnation method to prepare CuO/AC(activated carbon) composite materials of different CuO content and characterized them via scanning electron microscope(SEM), Brunauer–Emmett–Teller(BET), and Fourier transform infrared spectroscopy(FT-IR).The effect of CuO content on toluene adsorption/desorption was evaluated.We explored the reusability of AC and AC03(CuO modified AC with CuO loading 0.3 wt.%) adsorbents via toluene adsorption/desorption cycle testing.We used quasi-firstand quasi-second-order models, the Bangham model, and the Weber–Morris model to fit the toluene adsorption data.The introduction of CuO species evidently improved the adsorption performance of activated carbon toward toluene.The CuO content markedly affected the specific surface area, CuO dispersal, the numbers of oxygen-containing functional groups on the surface, and adsorption performance of the prepared composite adsorbents.Low CuO content was not favorable for the formation of active adsorption sites,while high content greatly reduced the specific surface area, and even covered active adsorption sites.The toluene adsorption performance varied in the order AC03 > AC02 >AC05 > AC08 > AC01(AC03, AC02, AC05, AC08 and AC01 are CuO modifying AC with CuO loading 0.3, 0.2, 0.5 0.8 and 0.1 wt.%, respectively).The breakthrough time and toluene adsorption capacity of the AC03 composite adsorbent were 94 min and 701.8 mg/g,respectively, and the recycling efficiency was 92.8% after thermal desorption at 200°C.The adsorption process was best described by the Bangham model and adsorption could be divided into three stages.

Diffusion behavior and reactions between Al and Ca in Mg alloys by diffusion couples

The diffusion behavior and reactions between AI and Ca in Mg alloys by diffusion couple method were investigated. Results demonstrate that Al2Ca is the only phase existing in the diffusion reaction layers. The volume fraction of Al2Ca in diffusion reaction layers increases linearly with temperature. The standard enthalpy of formation for intermetallic compounds was rationalized on the basis of the Miedema model. Al-Ca intermetallic compounds were preferable to form in the Mg-Al-Ca ternary system under the same conditions. Over the range of 350-400℃, the structure of Al2Ca is more stable than that of Al4Ca, Al14Ca13and Al3Ca8, The growth constants of the layer I, layer II and entire diffusion reaction layers were determined. The activation energies for the growth of the layer I, layer II and entire diffusion reaction layers were （80.74 ± 3.01 ） kJ/mol, （93.45 ±2.12） kJ/mol and （83.52 ±1.50） kJ/mot, respectively. In layer I and II, AI has higher integrated interdiffusion coefficients D^i^Int,layer layer than Ca. The average effective interdiffusion coefficients D^Al^eff values are higher than D^Ca^eff in the layer I and II.