Static and dynamic mechanical behaviour of ECO-RPC

Ecological reactive powder concrete (ECO-RPC) with small sized and differentvolume fraction steel fibers was prepared by substitution of ultra-fine industrial waste powder for50% to 60% cement by weight and replacement of ground fine quartz sand with natural fine aggregate.The effect of steel fiber volume fraction and curing ages on the static mechanical behaviour ofECO-RPC was studied. Using the split Hopkinson pressure bar technique, the dynamic mechanicalbehaviour of ECO-RPC was investigated under different strain rates. The results show that the staticmechanical behaviour of ECO-RPC increases with the increase of steel fiber volume fraction andcuring ages. The type of ECO-RPC with the substitution of 25% ultra-fine slag, 25% ultra-fine flyash and 10% silica fume is better than the others with compressive strength, flexural strength, andfracture energy more than 200 MPa, 60 MPa and 30 kJ/m^2, respectively. ECO-RPC has excellent strainrate stiffening effects under dynamic load. Its peak stress, peak strain and the area understrain-stress curve increase with the increase of strain rate. Its fracture pattern changes frombrittleness to toughness under high strain rates.

First-principles investigation on stability and electronic structure of Sc-dopedθ′/Al interface in Al−Cu alloys

The properties of Sc-dopedθ′(Al_(2)Cu)/Al interface in Al−Cu alloys were investigated by first-principles calculations.Sc-doped semi-coherent and coherentθ′(Al_(2)Cu)/Al interfaces(Sc doped in Al slab(S1 site),Sc doped inθ′slab(S2 site))were modeled based on calculated results and reported experiments.Through the analysis of interfacial bonding strength,it is revealed that the doping of Sc at S1 site can significantly decrease the interface energy and increase the work of adhesion.In particular,the doped coherent interface with Sc at S1 site which is occupied by interstitial Cu atoms has very good bonding strength.The electronic structure shows the strong Al—Cu bonds at the interfaces with Sc at S1 site,and the Al—Al bonds at the interfaces with Sc at S2 site are formed.The formation of strong Al—Cu and Al—Al bonds plays an important role in the enhancement of doped interface strength.

Determination of the Cement Sheath Interface and the Causes of Failure in the Completion Stage of Gas Wells

The bonding quality of the cement sheath interface decreases during well completion because of the change in the casing pressure.To explore the root cause of such phenomena,experiments on the mechanical properties and interface bonding strength of a cement sheath have been carried out taking the LS25-1 high-temperature and high-pressure(HTHP)gas field as an example.Moreover,a constitutive model of the cement sheath has been defined and verified both by means of a full-scale HTHP cement sheath sealing integrity evaluation experiment and three-dimensional finite element simulations.The results show that the low initial cementing surface strength is the root cause of cement sheath interface bonding failure.When the pressure in the casing exceeds a certain limit,the stress caused by the change in the internal pressure in the casing is transmitted to the cement sheath,resulting in the degradation of the interface stiffness of the cement sheath.However,with an increase in the casing wall thickness,the stress transmission capacity decreases.Therefore,it is concluded that improving the interfacial cementing strength,appropriately increasing the casing wall thickness and increasing the initial stress of the cement sheath are the keys to ensuring the sealing integrity of the cement sheath in high-temperature and high-pressure gas wells.

Experimental Research of Dynamic Response of Laser-Induced Film-Substrate System

Film-substrate’s interfacial bonding strength is closely related to film quality. An excellent interfacial bonding strength is the premise for the well use of film. The laser detecting technique of discrete scratches based on laser shockwave effect is a new method, which can measure interfacial bonding strength. With this technique, film-substrate system is of transient load of different laser energy, the relation between the dynamic response characteristics of such film-substrate system and film-substrate’s interfacial bonding strength is a core problem to be solved urgently. On this basis, this paper conducted research on the dynamic response characteristics of film-substrate system during laser loading process using detecting technique of PVDF patch sensor. Results show that under the irradiation of different laser energy, it can detect dynamic responses of theory models of different film-substrate system using PVDF patch sensor, wherein shockwave dynamic response and dynamic strain response are included. Laser energy and interfacial bonding strength are of a regular influence to the dynamic response of film-substrate system theory model.

Preparation and characterization of PVDF-glass fiber composite membrane reinforced by interfacial UV-grafting copolymerization

A novel inorganic-organic composite membrane,namely poly（vinylidene fluoride） PVDF-glass fiber（PGF） composite membrane,was prepared and reinforced by interfacial ultraviolet（UV）-grafting copolymerization to improve the interfacial bonding strength between the membrane layer and the glass fiber.The interfacial polymerization between inorganic-organic interfaces is a chemical cross-linking reaction that depends on the functionalized glass fiber with silane coupling（KH570） as the initiator and the polymer solution with acrylamide monomer（AM） as the grafting block.The Fourier transform infrared spectrometer-attenuated total reflectance（FTIR-ATR） spectra and the energy dispersive X-ray（EDX） pictures of the interface between the glass fiber and polymer matrix confirmed that the AM was grafted to the surface of the glass fiber fabric and that the grafting polymer was successfully embedded in the membrane matrix.The formation mechanisms,permeation,and anti-fouling performance of the PGF composite membrane were measured with different amounts of AM in the doping solutions.The results showed that the grafting composite membrane improved the interfacial bonding strength and permeability,and the peeling strength was improved by 32.6% for PGF composite membranes with an AM concentration at 2 wt.%.