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W. Ensinger - One of the best experts on this subject based on the ideXlab platform.

  • Thickness deviations of films deposited by ion beam assisted deposition under off-normal ion incidence
    Surface and Coatings Technology, 1994
    Co-Authors: B. Enders, R. Emmerich, W. Ensinger
    Abstract:

    Abstract Re-sputtering of already deposited material is a side effect of ion bombardment during film growth by ion beam assisted deposition (IBAD). This mostly undesirable effect leads to a reduction in film growth velocity. Because of this dynamic ion etching the actually deposited mass does not correspond to the evaporated mass as determined with a quartz crystal. This loss has to be accounted for by an increase in process time when a particular film thickness is required. The situation may become critical when the ion Impact Angle deviates from the surface normal, i.e. either when a plane substrate has to be tilted or when curved surfaces have to be coated. In the present study the deviations in film thickness are discussed for offnormal ion incidence IBAD. A mathematical expression is given which describes the dependence of the sputtering yield on the Impact Angle by fitting to experimentally obtained data. It is applied to calculate the dependence of film thickness deviations on the Particle Impact Angle. As an example for coating components with a curved surface, the data for cylinders and spheres were calculated. Lengthening factors are listed for different IBAD conditions such as sputtering yield and arrival ratio of atoms and ions, which determine the excess in process time or in evaporated material necessary to coat a cylinder homogeneously with a film of a desired thickness.

B. Enders - One of the best experts on this subject based on the ideXlab platform.

  • Thickness deviations of films deposited by ion beam assisted deposition under off-normal ion incidence
    Surface and Coatings Technology, 1994
    Co-Authors: B. Enders, R. Emmerich, W. Ensinger
    Abstract:

    Abstract Re-sputtering of already deposited material is a side effect of ion bombardment during film growth by ion beam assisted deposition (IBAD). This mostly undesirable effect leads to a reduction in film growth velocity. Because of this dynamic ion etching the actually deposited mass does not correspond to the evaporated mass as determined with a quartz crystal. This loss has to be accounted for by an increase in process time when a particular film thickness is required. The situation may become critical when the ion Impact Angle deviates from the surface normal, i.e. either when a plane substrate has to be tilted or when curved surfaces have to be coated. In the present study the deviations in film thickness are discussed for offnormal ion incidence IBAD. A mathematical expression is given which describes the dependence of the sputtering yield on the Impact Angle by fitting to experimentally obtained data. It is applied to calculate the dependence of film thickness deviations on the Particle Impact Angle. As an example for coating components with a curved surface, the data for cylinders and spheres were calculated. Lengthening factors are listed for different IBAD conditions such as sputtering yield and arrival ratio of atoms and ions, which determine the excess in process time or in evaporated material necessary to coat a cylinder homogeneously with a film of a desired thickness.

Carlos Roberto Camello Lima - One of the best experts on this subject based on the ideXlab platform.

  • Phase transformation of Nb2O5 during the formation of flame sprayed coatings and its influence on the adhesion strength, abrasive wear and slurry erosive wear
    Wear, 2019
    Co-Authors: Hipólito Carvajal Fals, Maria Júlia Xavier Belém, Angel Sánchez Roca, Leonardo Fanton, Carlos Roberto Camello Lima
    Abstract:

    Abstract The development of research related to the characterization of niobium pentoxide (Nb2O5) has been of great interest in the scientific and commercial community due to promising performances in bio-electrochemical applications, advanced catalysts and corrosive environments. In this work, layers of 250 µm, 350 µm and 550 µm of Nb2O5 were deposited by low-speed flame spray on NiAl-bond coated AISI 1020 steel substrates. The phase transformations of Nb2O5, which occur during the formation of the layers, were studied as a function of deposited thickness and further correlated with adhesion, abrasion and slurry erosion resistance. X-ray diffraction analyzes of the coatings were performed for the study of the phases in the process. Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) with dispersive energy microanalysis (EDS) were used to help microstructural analysis. The adhesive strength of the layers was evaluated by ASTM C633-13 and correlated with abrasion (ASTM G65-16) and slurry erosion wear resistance. From the microscopy analysis, a dense layer was observed with good interconnection at the interface Nb2O5-NiAl, with presence of pores typical of the thermal spray process. The XRD diffractograms of the niobium oxide coated samples show similar results regardless of the coating thickness (250, 350 and 550 µm) presenting superior compatibility with the hexagonal Nb2O5 and the monoclinic NbO2.46 (Nb22O54). The significantly higher intensities of the hexagonal Nb2O5 peaks suggest that it is the predominant phase. The thinner coatings, 250 and 350 µm, had higher adhesive strength, with a mean fracture stress of 16.12 MPa and 15.27 MPa, respectively. Nb2O5 thinner coatings showed also higher abrasive wear resistance when compared to "D2" tool steel and "H13" chrome tool steel. The thicker coatings (550 µm) had a mean adhesive strength of 13.73 MPa. From the abrasive wear tests, thicker coatings showed a greater volume loss of 41.18 mm3. The 550 µm coating presented higher slurry erosion resistance at a 30° Particle Impact Angle, with a lower volume loss (12.93 mm3).

  • Influence of Fracture Toughness and Microhardness on the Erosive Wear of Cermet Coatings Deposited by Thermal Spray
    Metallurgical and Materials Transactions A, 2017
    Co-Authors: Miguel Reyes Mojena, Mario Sánchez Orozco, Hipólito Carvajal Fals, Valtair Antonio Ferraresi, Carlos Roberto Camello Lima
    Abstract:

    An evaluation of the relationship between the microhardness and fracture toughness with resistance to erosive wear of WC10Co4Cr, WC-12Co, and Cr3C2-25NiCr coatings was conducted. Powder and flexible cored wire feedstock materials were applied by high-velocity oxygen fuel (HVOF) and flame spray (FS), respectively. The erosive wear mechanism prevailing in the coatings was found to be brittle, which also explains the higher erosion rate for the experimental condition using the Particle Impact Angle of 90 deg and Impact velocity of 9.33 m/s. The best wear performance was for the coatings applied by HVOF that attains 1.83 mm^3/kg for the 90 deg/3.61 m/s test condition. The coating obtained with the WC-10Co4Cr material using the FSFC method showed tungsten carbide decarburization, justifying its poor mechanical properties and poor performance in the erosive wear test. Flame-sprayed flexicords proved to be a promising alternative to HVOF in obtaining coatings with low porosity and acceptable mechanical properties, especially in applications where the use of the HVOF technique is inadequate because of inaccessibility or excessively high cost. Values of K _c for the coatings obtained by HVOF (7.35 to 10.83 MPa.m^1/2) were between two and three times greater than the values obtained for the coatings resulting from FSFC (2.39 to 3.59 MPa.m^1/2), in a similar manner as with the microhardness.

R. Emmerich - One of the best experts on this subject based on the ideXlab platform.

  • Thickness deviations of films deposited by ion beam assisted deposition under off-normal ion incidence
    Surface and Coatings Technology, 1994
    Co-Authors: B. Enders, R. Emmerich, W. Ensinger
    Abstract:

    Abstract Re-sputtering of already deposited material is a side effect of ion bombardment during film growth by ion beam assisted deposition (IBAD). This mostly undesirable effect leads to a reduction in film growth velocity. Because of this dynamic ion etching the actually deposited mass does not correspond to the evaporated mass as determined with a quartz crystal. This loss has to be accounted for by an increase in process time when a particular film thickness is required. The situation may become critical when the ion Impact Angle deviates from the surface normal, i.e. either when a plane substrate has to be tilted or when curved surfaces have to be coated. In the present study the deviations in film thickness are discussed for offnormal ion incidence IBAD. A mathematical expression is given which describes the dependence of the sputtering yield on the Impact Angle by fitting to experimentally obtained data. It is applied to calculate the dependence of film thickness deviations on the Particle Impact Angle. As an example for coating components with a curved surface, the data for cylinders and spheres were calculated. Lengthening factors are listed for different IBAD conditions such as sputtering yield and arrival ratio of atoms and ions, which determine the excess in process time or in evaporated material necessary to coat a cylinder homogeneously with a film of a desired thickness.

H. Nayeb-hashemi - One of the best experts on this subject based on the ideXlab platform.

  • The Effect of Solid Particle Erosion on the Mechanical Properties and Fatigue Life of Fiber-reinforced Composites
    Journal of Composite Materials, 2006
    Co-Authors: N. H. Yang, H. Nayeb-hashemi
    Abstract:

    The effect of solid Particle erosion on the strength and fatigue properties of E-glass/epoxy composite is investigated. Solid Particle erosion with SiC Particles of 400–500 μm in diameter is simulated on 12-ply [45°/–45°/0°/45°/–45°/0°]S E-glass/epoxy composites with a constant Particle velocity of 42.5 m/s and a solid Particle to air volume ratio of 6 kg/m3 at Impact Angles of 90, 60, and 30° for 30, 60, 90, and 120 s. Damaged and undamaged specimens are subjected to tensile tests while monitoring their acoustic emission (AE) activity. An erosion damage parameter is defined as a function of the Particle Impact Angle and the erosion duration to determine the residual tensile strength of the composite. Scanning electron microscope (SEM) images of the erosion-damaged specimens reveal that the same damage mechanism occurs at different Impact Angles. The AE stress delay parameter is used to predict the residual tensile strength of erosion-damaged composites. Tension–tension fatigue tests are performed on virg...

  • The Effect of Solid Particle Erosion on the Mechanical Properties and Fatigue Life of Fiber-Reinforced Composites
    Materials Nondestructive Evaluation and Pressure Vessels and Piping, 2006
    Co-Authors: N. H. Yang, H. Nayeb-hashemi
    Abstract:

    The effect of solid Particle erosion on the strength and fatigue properties of E-glass/epoxy composite was investigated. Solid Particle erosion with SiC Particles of 400 μm to 500 μm in diameter was simulated on 12 ply [45°/-45°/0°/45°/-45°/0°]s E-glass/epoxy composites with a constant Particle velocity of 42.5 m/s and solid Particle to air volume ratio of 6 kg/m3 at Impact Angles of 90°, 60°, and 30° for 30, 60, 90 and 120 seconds. Damaged and undamaged specimens were subjected to tensile tests while monitoring their acoustic emission (AE) activity. An erosion damage parameter was defined as a function of the Particle Impact Angle and erosion duration to determine the residual tensile strength of the composite. Scanning electron microscope (SEM) images of the erosion damaged specimens revealed the same damage mechanism occurred at different Impact Angles. The AE stress delay parameter was used to predict the residual tensile strength of erosion damaged composites. Tension-tension fatigue tests were performed on virgin specimens and specimens exposed to erosion damage of 60 seconds and 90 seconds at 90° Particle Impact Angle to observe the effects of erosion damage on the fatigue life. A modified Basquin's equation was defined to predict the fatigue life of the erosion damaged specimens.Copyright © 2006 by ASME

  • Evaluation of Solid Particle Erosion Damage on E-Glass/Epoxy Composites Using Acoustic Emission Activity
    Nondestructive Evaluation Engineering, 2005
    Co-Authors: N. H. Yang, H. Nayeb-hashemi
    Abstract:

    The effect of solid Particle erosion on the strength properties of E-glass/epoxy composite was investigated. Solid Particle erosion with SiC Particles 400 μm to 500 μm in diameter was simulated on 12 ply [45°/−45°/0°/45°/−45°/0°]s E-glass/epoxy composites with constant Particle velocity of 42.5 m/s at Impact Angles of 90°, 60°, and 30° for 30, 60, 90 and 120 seconds. Damaged and undamaged specimens were subjected to tensile tests while monitoring their acoustic emission (AE) activity. An erosion damage parameter was defined as a function of the Particle Impact Angle and erosion duration to determine the residual tensile strength of the composite. Scanning electron microscope (SEM) images of the erosion damaged specimens revealed the same damage mechanism occurred at different Impact Angles. The distribution of AE events by event duration, ring down counts and energy distribution were used to characterize the different damage mechanisms that occurred during tensile loading of damaged and undamaged specimens. The results showed AE activity could be used to distinguish between different damage mechanisms within the composite, such as fiber/matrix debonding, delamination and fiber fracture. The Weibull probability distribution model and the AE stress delay parameter model were developed to relate the AE activity to the erosion damage and residual strength. The results showed both the Weibull probability model and the stress delay model could be used to predict residual strength of the composites.Copyright © 2005 by ASME