Abrasive mechanisms and interfacial mechanics of amorphous silicon carbide thin films in chemical-mechanical planarization

2021

Sci Rep

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Evaluating the effect of porosity and ambient temperature on mechanical characteristics and thermal conductivity is vital for practical application and fundamental material property. Here we report that ambient temperature and porosity greatly influence fracture behavior and material properties. With the existence of the pore, the most significant stresses will be concentrated around the pore position during the uniaxial and biaxial processes, making fracture easier to occur than when tensing the perfect sheet. Ultimate strength and Young’s modulus degrade as porosity increases. The ultimate strength and Young's modulus in the zigzag direction is lower than the armchair one, proving that the borophene membrane has anisotropy characteristics. The deformation behavior of borophene sheets when stretching biaxial is more complicated and rough than that of uniaxial tension. In addition, the results show that the ultimate strength, failure strain, and Young’s modulus degrade with growing temperature. Besides the tensile test, this paper also uses the non-equilibrium molecular dynamics (NEMD) approach to investigate the effects of length size, porosity, and temperature on the thermal conductivity (κ) of borophene membranes. The result points out that κ increases as the length increases. As the ambient temperature increases, κ decreases. Interestingly, the more porosity increases, the more κ decreases. Moreover, the results also show that the borophene membrane is anisotropic in heat transfer.

Section: Introductionmentioning

confidence: 99%

Understanding porosity and temperature induced variabilities in interface, mechanical characteristics and thermal conductivity of borophene membranes

Pham

2021

Sci Rep

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“…As an alternative approach, MD simulation can be utilized to analyze very large systems, with thousands to millions of atoms 30 . Additionally, as a complement to the experimental test, MD simulation is a helpful tool to deepen the understanding of the mechanical and thermal properties at the nanoscale [31][32][33][34][35] .…”

mentioning

confidence: 99%

Effects of temperature and intrinsic structural defects on mechanical properties and thermal conductivities of InSe monolayers

Pham

2020

Sci Rep

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We conduct molecular dynamics simulations to study the mechanical and thermal properties of monolayer indium selenide (InSe) sheets. The influences of temperature, intrinsic structural defect on the tensile properties were assessed by tensile strength, fracture strain, and Young’s modulus. We found that the tensile strength, fracture strain, and Young’s modulus reduce as increasing temperature. The results also indicate that with the existence of defects, the stress is concentrated at the region around the vacancy leading to the easier destruction. Therefore, the mechanical properties were considerably decreased with intrinsic structural defects. Moreover, Young’s modulus is isotropy in both zigzag and armchair directions. The point defect almost has no influence on Young’s modulus but it strongly influences the ultimate strength and fracture strain. Besides, the effects of temperature, length size, vacancy defect on thermal conductivity (κ) of monolayer InSe sheets were also studied by using none-equilibrium molecular dynamics simulations. The κ significantly arises as increasing the length of InSe sheets. The κ of monolayer InSe with infinite length at 300 K in armchair direction is 46.18 W/m K, while in zigzag direction is 45.87 W/m K. The difference of κ values in both directions is very small, indicating the isotropic properties in thermal conduction of this material. The κ decrease as increasing the temperature. The κ goes down with the number of atoms vacancy defect increases.

“…At 5.0 Å depth, the numbers of atoms removed in rolling motion were also greater than the sliding one. However, the speed of increasing the removed atoms was slower than the previous depths as the abrasive surface suffered a saturated phenomenon [49]. At 10 Å depth, the numbers of atoms removed in rolling motion were smaller than the sliding one.…”

Section: Three-body Contact Polishingmentioning

confidence: 92%

Atomistic wear mechanisms and deformation evolution in polishing

Nguyen

2020

Preprint

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Our aim with this study was a new insight into the sub-nanoscale of polishing and provides the atomic view of the material removal and wear mechanisms by carrying out molecule dynamics simulation. We proposed and analyzed a model with a diamond abrasive particle that sliding or rolling on the surface of GaN workpieces. The authors investigated, step by step, the effects of polishing depths, speeds, abrasive sizes, and crystalline orientations on the wear mechanisms and material removal. The wear mechanisms of the sliding motion were adhering, ploughing, and cutting, depending on the depths. While the wear mechanisms of rolling motion are adhering and ploughing. Notably, in both stages of sliding and rolling, there is an existence of a critical point at 5.0 Å depth when we considered the deformation behaviors. Below that critical point, the GaN workpiece will present an elastic deformation. From the aforementioned point, the workpiece would be plastically deformed. Besides, from 10 Å depth, the dislocation began to appear and evolute simultaneously with the development of the maximum shear stress. The sliding motion on the Ga-face could remove a greater number of atoms than that of the N-face. Moreover, direction [1-100] on Ga-face requesting more forces to polish than direction [11-20]. In conclusion, the main achievements that contribute to the field can be summarized as follows: the atomistic wear mechanisms of sliding and rolling motions, material removal, and the role of rolling motion at the sub-nanoscale during the ultrafine flat polishing process.