Largest Work Of Adhesion Research Articles

First-principles study of NbC/Nb interface stability and electronic structure

The NbC/Nb composite layer can be fabricated on the surface of refractory metal Nb by in-situ hot pressure diffusion method. The interface bonding, coherent mismatch and stability of the NbC/Nb microphase interface should be valued because they are important for the improvement of the properties of the composite layer. This study investigated the interactions between atoms at the NbC/Nb interface, considering the first-principles approach of density functional theory. Six interface models were constructed, and the density of states, work of adhesion, formation enthalpy, Mulliken analysis and charge density were mainly analyzed when the NbC/Nb interface was Nb terminal and C terminal respectively. The Nb(100)-NbC(001)C interface exhibited the lowest density of states at the Fermi energy level, the largest adhesion work (0.84 J/m2) and the smallest formation enthalpy. In the interface of Nb(100)-NbC(001)C, Nb and C form a covalent bond, which has the largest number of layouts and the shortest bond length, showing strong stability that cannot be easily broken.

Investigation on the interface properties of Be-Al alloys via first-principles calculation

In this paper, the Be/Al pure interface is constructed using First-principles calculation. Among the six interface structures, the interface adhesion work calculation results show that the Be (001)/Al (100) interface has the largest adhesion work (2.48 J/m2), which proves that the Be (001)/Al (100) interface is the most stable interface structure. Also, the Be (001)/Al (100) composite interface structure doping elements of Ni, Ag, Co and Ge was constructed. The results of segregation heat and interface adhesion work calculation showed that the addition of Ni, Ag and Co was beneficial to the improvement of the Be (001)/Al (100) interface strength. The doping effect of Ag and Co is similar, followed by Ni, and the doping of Ge leads to the degradation of interface properties. The calculation results of the partial density of states (PDOS) and the charge density difference show that in the pure Be (001)/Al (100) interface structure, a metallic bond is formed between Be and Al atoms near the interface. With the introduction of doping elements, the charge between Be and Al atoms is redistributed. A stronger new metal bond of Be-X or Al-X (X=Ni, Ag, Co) is formed, but the doping of Ge elements forms a weaker Be-Ge metal bond, which is not conducive to the performance improvement of Be-Al alloys.

First-principles investigation on the tensile strength, interfacial stability and electronic structure of the heterogeneous nucleation Al/VB2 interfaces

First principles calculations based on the density functional theory were performed on the interfacial properties of Al(111)/VB2(001) and Al(100)/VB2(100) interfaces including interfacial stability, bonding features and tensile strength. Fourteen different interfaces with different VB2 terminations (V-terminated and B-terminated) were studied. The convergence test shows that 7-layered Al(111) and 9-layered Al(001), 9-layered VB2(001) and 13-layered VB2 (100) are thick enough to build Al/VB2 interface. The (001)-V-hcp and (100)-V-cen site interface have the largest work of adhesion (Wad) among the Al(111)/VB2(001) and Al(100)/VB2(100) interfaces. And under V-rich condition, there interfacial energies are − 0.44 J/m2 and − 0.45 J/m2 which are much lower than 0.15 J/m2, indicating it is an effective heterogeneous nucleation substrate for α-Al. The main bonding characteristics is metallic for the (001)-V-hcp interface, while it is covalent with metallic for the (100)-V-cen interface, making it has the largest Wad. The calculated tensile strength of (001)-V-hcp site interface is about 7.36Gpa when the strain is 12 %. While it is 6.27Gpa for the (100)-V-cen site interface at 10 %. Finally, the VB2 particles are proved to be an effective heterogeneous nucleation substrate for α-Al as observed from experiment.

First-principles study on interfacial structure and strength of SiC/VC nano-layered hard coatings

The interfacial and strength properties of SiC/VC nanolayered hard coatings have been studied by using first-principles. Four SiC (0001)/VC (111) interface models are constructed for searching the stable interface configure of SiC/VC coatings. Due to C-C termination is much stronger than C-V, C-Si, Si-V terminations, the SiC1-VC2 interface has the largest adhesion work and the lowest interface energy than other models. Griffith work and fracture toughness analysis show that the mechanical failure of the coating begins at the interface between SiC and VC. The electronic structure of SiC/VC interface indicate that the interfacial bonding strength related to hardness is mainly determined by V-d, C2-p and Si-p orbitals.

First-principles study of interfaces in Al/SiC metal-matrix composite system

First-principles calculations were performed on the interfaces between Al and SiC, which is a widely used strengthening agent in aluminum metal-matrix-composites (Al/MMC). C-terminated interfaces have much larger work of adhesion than Si-terminated interfaces, indicating that the former has much stronger interfacial bonding. The electron localization function shows that the chemical bonding between Al and C has a strong covalent character, while the bonding between Al and Si is largely metallic. As a result of the vastly different chemical bonding, the work of adhesion for C-terminated interfaces increases with the number of dangling bonds at the interface, while the opposite trend was observed for Si-terminated interfaces. Additionally, the interface energy for Si-terminated interfaces is comparable to that for C-terminated interfaces, suggesting both types of terminations can coexist in the Al/SiC system.

Effect of N–Cr compounds on the brazing of high nitrogen steel with Ag-based filler metal: first-principles calculation

The Cr element is present in the form of CrN and Cr2N compounds in the brazing of high nitrogen steel with Ag-based filler metals. The Cr compounds have a strong influence on the strength of the brazed joints. In this paper, the mechanical properties of CrN and Cr2N are evaluated based on first-principles. The results show that Cr2N has a stronger covalent bonds than CrN, resulting in higher Young's modulus and hardness of Cr2N than CrN. The 7 atomic layers Ag(111) surface, 9 atomic layers CrN(111) surface and 9 atomic layers Cr2N(0001) surface can represent the block structure. The Ag(111)/CrN(111) interface and Ag(111)/Cr2N(0001) interface were constructed. The Ag(111)/CrN(111) B-site interface was found to have the largest work of adhesion(Wad). The chemical bonding strength of Ag–N in the Ag(111)/CrN(111) interface is stronger than that in Ag(111)/Cr2N(0001) interface, indicating that the formation of Cr2N phase is more likely to produce microcracks in brazing joints. Hence, the formation of the Cr2N phase should be suppressed.

Probing the stability, adhesion strength, and fracture mechanism of Mg/Al2Y interfaces via first-principles calculations

The interface is the “link bridge” between the reinforced phase and the matrix, and its microstructures and configurations will directly affect the overall performance of composites. In this work, the atomic configurations, electronic properties, interfacial stability, and adhesion strength of Mg(0001)/Al 2 Y(100) interfaces with Al and Y termination were studied using first-principles calculations. The current first-principles study results elucidated that the Al 2 Y(100)_Al surface has the most thermodynamically stability compared to other two surfaces with Al termination in the whole range of the yttrium chemical potential ( μ Y s l a b − μ Y b u l k , Δ μ Y ). Additionally, the Al 2 Y(100)_Y surface was less stable than the Al 2 Y(100)_Al surface when Δ μ Y < -0.64 eV; otherwise, Al 2 Y(100)_Y surface was more stable. Moreover, the Y-HCP configuration has the largest work of adhesion in all configurations of Mg(0001)/Al 2 Y(100) interface. Moreover, the interfacial energy of the Al-MT and Y-HCP configurations were 1.29~0.29 J/m 2 and 0.76~1.77 J/m 2 , respectively. Owing to the bonding strength between Y (Al) and Mg atoms near the interface, the tensile stress of the Mg(0001)/Al 2 Y(100) with Y-HCP (Al-MT) configuration has the largest value compared to other Y terminated (Al terminated) configurations, and the mechanical failure eventually occurs in the Mg (0001) slab. • The Al 2 Y (100) has the most thermodynamically stability compared to the others two low index surfaces. • The predicted critical tensile stress of Al-MT is approximately of 6.5 GPa. • The mechanical failure of Mg(0001)/Al 2 Y(100) interface eventually occurs in the Mg (0001) slab.

A comparable study of Fe/Cu interfaces by first-principles method: The surface energy, work of adhesion and electronic structures

Iron–Copper composite was prepared by casting method, and the interface bonding strength of Fe and Cu was investigated. In this paper, density functional theory (DFT) based on first-principle was carried out to analyze two different atomic stacking sequences (Cu-on-Fe and Cu-center-Fe) on the interface properties, including electronic density of states, charge density difference and partial density of states. The results show that with the larger work of adhesion (Wad), the Cu-center-Fe interface is more stable than Cu-on-Fe interface. It can be found that the bonding energy of the interface is the larger and stable interface when the Fe atom on the Fe (001) plane is bound to the Cu (001) plane, and Fe–Cu metal bond is formed at the interface and the bonding strength of the interface is increased. The EDS analysis on the Fe/Cu interface reveals the element distribution in the fusion zone is relatively uniform.

Revealing the interface characteristic of the semi-coherent Co(111)/WC(0001) interface: a first principles investigation

ABSTRACT In the present work, based on the first-principles calculations, we systematically discuss the electronic structure, adhesion work, interface energy, chemical bonding strength and interfacial mechanical failure forms of semi-coherent Co(111)/WC(0001) interface. After relaxation, the interface configurations of the middle top (MT) sites migrate toward the hexagonal close-packed hollow top sites (HCP), indicating that the MT occupancy is unstable. The atoms at the interface are more inclined to the HCP sites. The calculated results indicate that the C-terminated HCP1 site interface configuration has the largest adhesion work and the smallest interface energy, which depends on the formation of strong C-Co covalent bonds at the interface. Finally, the strong Co/WC interface configuration formed in the WC-Co composites can effectively carry out load transfer and reduce stress concentration, improving the strength and plasticity of the composites.

The Stability and Electronic Structure of Cu(200)/AuCu(200) Interface: An Insight from First-Principle Calculation.

AuCu phase had a significant effect on the bonding strength of Au80Sn20 alloy and Cu substrate. The formation of the AuCu(200)/Cu(200) interface significantly improves the shear strength of solder joints. Therefore, it is particularly important to analyze the strengthening mechanism of the AuCu phase in the Cu matrix. The atomic structure, interfacial stability, and interfacial bonding properties of the Cu(200)/AuCu(200) interface were investigated using first-principle calculation. The layer spacing convergence results show that seven layers of Cu(200) surface and seven layers of AuCu(200) surface are enough thick to be chosen for the interface model. The calculation shows that the surface energies are 1.463 J/m2 and 1.081 J/m2 for AuCu(200) surface and Cu(200) surface, respectively. Four interface combinations of Top sit, Long bridge, Short bridge, and Hollow were investigated by considering four stacking methods of AuCu(200). It is shown that the interfacial configuration of the Long bridge is the most stable and favorable structure, which has the largest adhesion work, the smallest interfacial energy, and the smallest interfacial spacing. The density of states and electron difference density were calculated for the four interfacial configurations, and the results showed that the main bonding mode of the Long bridge interface is composed of both Cu-Cu covalent bonds and Au-Cu covalent bonds.

TiN inducing ferrite nucleation based on the bcc-Fe/TiN interfaces formation at atomic scale by first-principles calculation

The Fe/TiN interface is commonly found in steel and the interface with low interfacial energy can promote the refinement of microstructure and improve the strength and toughness of the material. In this paper, Fe(100)/TiN(100) and Fe(110)/TiN(110) interface with low mismatch are investigated by first-principles calculation. Six specific geometry models with different stacking positions (TS, CS and HS) are established. The results show that after geometric optimization, the interfaces with TS stacking sequence and CS stacking sequence have little change, while the interfaces with HS stacking sequence transforms into CS stacking. The Fe(110)/TiN(110) interface with CS stacking possesses the best interfacial bonding strength as the largest adhesion work and the Fe(100)/TiN(100) interface with CS stacking possesses the best stability as the lowest interfacial energy. The main component bonding of interface-1, 2 and 3 is mixture of covalent and metallic. In addition, in the process of TiN introducing ferrite nucleation, Fe atoms are more likely to gather on TiN(100) surface and form the Fe(100)/TiN(100) interface by layer-by-layer extrapolation. The Fe(100)/TiN(100) interface as the most stable interface can provide a basis for the optimal design of TiN-induced ferrite nucleation.

Promoting wetting of Mg on the SiC surfaces by addition of Al, Zn and Zr elements: A study via first-principle calculations

When preparing SiC/Mg composites, alloy elements play key roles in the nucleation and interfacial wetting. In this paper, effects of Al, Zn and Zr additions on the Mg/SiC interfacial bonding properties were investigated comprehensively via method of first-principle calculations. Mg(0001)/SiC(0001) interfaces with different terminations and stacking sequences were built and C Ⅱ-T C Ⅱ top interface has the largest work of adhesion (Wad). Zn dopants can not improve the Wad for both C-T and Si-T interfaces. Al atom can only strengthen the C-T interface. Zr addition can greatly improve the Wad for both C-T and Si-T interfaces. Wad of C-T interfaces can reach up to 11.55 J/m2 and 12.55 J/m2 after doping 1 monolayer (ML) of Al and Zr atoms. Larger Wad can lead to lower contact angles of Mg on SiC surfaces, which can improve wetting and nucleation in SiC/Mg composites. Analysis of electronic structure shows that Al-C and Zr-C bonds have more covalent composition than the Mg-C bond, which is responsible for the improvement of interfacial bonding strength. Experimental results in references were also analyzed, which are in well agreement with our calculation results.

Investigation on the interface characteristic between ZrC (111) and diamond (111) surfaces by first-principles calculation

The interface structure, interfacial stability and wettability, as well as bonding characteristics of ZrC(111)/diamond(111) interfaces have been investigated systematically by performing first-principles calculations. Taking into account two terminations of ZrC (111) and three types of stacking sequences, six possible interface models were investigated. The calculated results indicated that the interface configuration, which C-termination ZrC(111) surface occupies on the bridge of diamond (111) surface, is the most stable and favorable structure with the largest adhesion work and smallest interface energy among six different models. Furthermore, the C-termination ZrC (111) surface is considered to wet well on diamond (111) surface based on the results of calculated contact angles. Moreover, it can be concluded from electron density difference and density of states that the most stable interface configuration is mainly composed of interfacial covalent CC bond hybridized by C 2p orbits.

Insights into the atomic scale structure, bond characteristics and wetting behavior of Cu(001)/Cu6Sn5(110) interface: A first-principles investigation

The atomic scale structure, interfacial bond characteristics and wetting behavior of Cu(001)/Cu6Sn5(110) interface have been investigated by means of first-principles calculations. It is revealed that the surface energies of Cu(001) and Cu6Sn5(110) surface with more than five layers can be converged to 1.45 J/m2 and 0.50 J/m2, respectively. It can be concluded that the Interface V, which the Cu atoms of the Cu(001) side are located on the hollow position of the Cu6Sn5(110) side, is the most stable configuration with the smallest interfacial distance, the largest adhesion work and the lowest interfacial energy. The contact angles of five interface configurations were also calculated. The analysis of density of states, electronic density difference, and Mulliken population indicated that the bond characteristics of Cu(001)/Cu6Sn5(110) interface are mainly composed of Sn–Cu and Cu–Cu covalent bonds.

First-principles calculation of interfacial stability, energy, electronic properties, ideal tensile strength and fracture toughness of SiC/BN interface

The interfacial properties and electronic structure of $$\beta$$ -SiC (111)/ $$h$$ -BN (0001), including work of adhesion (Wad), interface energy, bonding nature, ideal tensile strength and fracture toughness, were investigated using first-principles calculations. Eight interface models, with two different terminations and four stacking sites, were investigated. The $$\beta$$ -SiC (111) slab, with 10 atomic layers, and the $$h$$ -BN (0001) slab, with two atomic layers, exhibited bulk-like interior features, respectively. The Case II interface, in which the Si atom was located at the center of the B-N bond, had the largest work of adhesion (2.749 J/m2), the smallest interfacial distance (2.02 A), the minimum interface energy (0.473 J/m2) and, thus, the best stability. The valence electron density and partial density of states indicated that there was a strong chemical and electrical interaction between the two sides of the Case II interface. The electronic structure analysis suggested that the interfacial bonding was mainly attributed to the Si-N ionic interaction and the valence electronic hybridization between Si-sp and B-sp. The ideal tensile strength and fracture toughness of the Case II interface were predicted as 13.26 GPa and 0.68–1.887 MPa•m1/2, respectively.

The interfacial structure of α-Ti/TiC in graphene-reinforced Ti6Al4V matrix composite coating prepared by laser cladding: first-principles and experimental

The α-Ti (0001)/TiC (111) interface was studied by first-principles calculations and experiments. Two atomic terminals and four interface models have been established by first principles. Good agreement has been observed between our calculation and experimental data. Moreover, from the results of calculations, the C-termination-hollow-sited interface had the smallest interfacial distance (2.078 A), the minimum interface energy ( − 3.401 J/m2), and the largest work of adhesion (3.102 J/m2), which was the most stable. By studying the charge density, charge density difference, and the partial density of states (PDOS), Ti-C covalent bonds and Ti–Ti metallic bonds are formed across the interface, which increased interfacial bonding strength. However, the interfacial bonding is more mainly contributed from the Ti-C covalent bonds.

First-principles study of the Ti/Al3Ti interfacial properties

In order to theoretically clarify the interface properties of the Ti/Al3Ti laminated composites, based on the interface orientation relationship characterized by electron back scattering diffraction technology, the adhesion work, electronic structure and bonding properties of the Ti/Al3Ti interfaces were calculated by first-principles calculations. Four Ti(0 0 0 1)/Al3Ti(001) models with different terminations (Al-terminated and Al + Ti-terminated) and different stacking sites (top-sites, and center-sites) were investigated. Results showed that the Al3Ti(001) surface energies of Al + Ti-termination (1.96–2.53 J/m2) are higher than that of Al -termination (1.87–1.29 J/m2), which indicates that the Al-terminated surface is more stable; Al-termination-center-sited model has the largest adhesion work (3.202 J/m2) and the strongest charge interaction, which is the best stability among the four Ti/Al3Ti interfaces; The calculated PDOS suggests that the interfacial bond of Al-termination-center-sited interface is the Al - Ti covalent bond, it is the result of the hybridization between the Ti-3d and Al-3p, and the interior atoms in A13Ti (001) slab have more covalent features than the interfacial atoms.

The interface properties of defective graphene on aluminium: A first-principles calculation

The interfacial properties of graphene/Al composites are of critical important for exploring its high mechanical performance. To improve the mechanical properties, many experimental works have been done in past decades, however, the understanding of their physical mechanisms are limited. Here, the electronic structures and interfacial adhesion properties of pristine/virous deficient graphene(001)/Al(111) interfaces are calculated by first-principles method. Results show that single vacancy defective graphene (SVG)/Al interface has larger work of adhesion (Wad) of 5.62 J/m2 than the pristine (Wad of 1.03 J/m2) and other defective graphene/Al interfaces (Wad of 5.12 J/m2 for boron doped single vacancy defective graphene (BVG)/Al and Wad of 5.12 J/m2 for double vacancy defective graphene (DVG)/Al, respectively) due to the strong hybridization of Al-2p and C-2p orbits, which giving rise to the formation of polar covalent bonds with the bond populations of 0.62–0.72 at the deficient site The corresponding interface spacing decreasing from 2.72 Å (Pristine Gra/Al) to 2.17 Å (SVG/Al). And the defective graphene doped by B atoms could inhibit the interaction between Al and C atoms in the BVG/Al interface. Comparing with the SVG and BVG cases, the interface interaction strength of DVG/Al interface decreases due to the formation of octatomic ring, which could cape the carbon dangling bond and lead to a small structure deformation of graphene. However, it maintains a high Wad of 3.98 J/m2, indicating a better interface bonding strength than idea Gra/Al.

Molecular dynamics simulation on the adhesion mechanism at polymer‐mold interface of microinjection molding

AbstractIn the demolding process of microinjection molding, the defects of microstructures are often caused by the strong adhesion between polymer and mold. In order to study the adhesion mechanism, the molecular dynamics (MD) method was proposed to simulate the adsorption of cycloolefin copolymer (COC) molecules on mold surfaces. The evolution snapshots of COC molecular chains of three interfacial models were obtained to directly demonstrate the adhesive strength of interfaces. Meanwhile, the work of adhesion, the relative concentration, the potential energy, and the radial distribution function (RDF) were calculated to explain the interaction mechanism of polymer‐mold interfaces. The simulation results showed that the COC‐Ni interface had the largest work of adhesion and the lowest potential energy, compared with other two interfaces. The van der Waals (VDW) energy, which mainly derived from the interaction between H atoms in COC and the mold material was the only nonbond interaction energy at the COC‐Ni and COC‐Si interfaces, while the electrostatic energy existed in COC‐Al2O3 interface. In order to reduce the adhesion between polymer and mold, fluorine (F) element could be doped into the Ni mold.

First-principles calculation of the interface stability of 3C-SiC(111)/Mg(0001)

The first-principles plane wave pseudopotential method based on density functional theory was used to study four SiC(111)/Mg(0001) interface models, and the ideal work of adhesion, charge density distribution, charge density difference and Mulliken population of the four interface models were calculated. The calculation results show that the structure of four interface models has not changed significantly, except for the more or less decrease in the interface spacing after geometry optimization. The Center-site interface of the C-terminated has the largest work of adhesion and the smallest interface spacing, which is the most stable structure among the four models. The calculation of the electronic structure shows that interfacial bonding of these two terminated interfaces of Center-site is a mixture of covalent and ionic bonds.