Papers by Keyword: Profilometry

Abstract: The fabrication of high-quality 4H-SiC epitaxial layers for power semiconductor devices involves complex processes including bulk crystal growth, wafer slicing, polishing, and chemical vapor deposition (CVD) epitaxy with precise step-flow control on slightly off-cut Si-face substrates. Despite advances, intrinsic crystallographic defects such as threading dislocations, basal plane dislocations, and stacking faults remain significant challenges, propagating into epitaxial layers and degrading device performance and reliability. This study examines defect types and their impact on 4H-SiC wafers, emphasizing the transition from 150 mm to 200 mm substrates, which introduces increased defect densities and polytype inclusions. Comprehensive defect characterization using advanced microscopy, molten KOH etching, and electrical wafer sorting reveals strong correlations between physical defects—such as micropipes, carrot-like stacking faults, and triangular 3C-SiC inclusions—and device failures, particularly under reliability stress tests like High Temperature Reverse Bias (HTRB). The findings highlight the critical role of substrate quality, epitaxial growth conditions, and defect mapping in improving yield and device robustness. This work underscores the necessity of integrating multi-scale defect inspection and targeted reliability assessments to optimize 4H-SiC power device manufacturing and performance.

Abstract: Automation of welding with robotic arms has become an inevitable trend in modern manufacturing technologies. This process can be automated by using a "click and go" in which the robot will weld a line where the spot is described or by using an in-line tracking algorithm in which the robot will choose the spot where to weld the line in each layer. This paper presents a simple methodology for the reconstruction of the weld joint and the classification of the joint geometry to serve as a first step to the automatic determination of the robot trajectory. The weld joint has been reconstructed using a laser profilometer placed as a tool on the robot. Spurious data has been removed by signal processing. The joint has been reconstructed three-dimensionally. The classification of the joint profiles was generated using an algorithm based on signal processing and artificial intelligence. This algorithm has been tested for the classification of V-joints (bevel-bevel) and single bevel joints.

Abstract: The nanocrystalline diamond films were deposited by microwave plasma enhanced chemical vapour deposition (PE-CVD) on Si (100) substrate. Reciprocating sliding tests were conducted using Si₃N₄ balls as a counter body. A method based on the construction of the Abbott curve representing the areas of pristine and worn surface in the wear scars was applied for estimation of the wear rate. The calculated wear rates were compared with the results obtained by profilometric measurements and direct measurement of the wear scars cross sections by scanning electron microscopy (SEM).

Abstract: The study deals with the calculation of the wear rate of nanocrystalline diamond (NCD) films. The NCD films were grown by microwave plasma enhanced chemical vapor deposition (MW-PECVD) on (100)-oriented Si wafers. Reciprocating sliding tests with different loads and test durations were conducted. The depth profiles of wear scars were analyzed by the mechanical (stylus) profilometer and the wear rate was evaluated. The NCD films were broken across the wear scars and the wear rate was estimated by the measurement of the area of wear scar using the scanning electron microscopy (SEM) cross-sectional image. A good agreement was found between two methods.

Abstract: Austenitic materials have high demand in modern manufacturing industries due to their improved technological characteristics such as high mechanical strength and hardness, corrosion resistance, heat resistance and wear resistance. Some applications of austenitic materials include elevated pressure and temperature, and require stringent design requirements and close tolerances in manufactured products. Laser cutting is one of the non-conventional cutting processes, used to obtain complex shapes and geometries. In this paper, laser cutting was performed on austenitic material. The laser cutting process parameters are varied with the aim to obtain the optimal process parameters. The geometric and metallurgical characteristics of the cut parts are investigated and compared to the conventional cutting methods of austenitic materials.

Abstract: The researches have concerned cavitation erosion of AlSi7Mg and AlSi11Mg aluminium casting alloys. The alloys have been investigated in the as-cast condition and after the precipitation hardening. The cavitation erosion tests were performed using vibratory cavitation erosion equipment in 5 minutes. Resistance to cavitation of tested materials was estimated by means of MDE (mean depth of erosion) parameter according to ASTM G32. After the cavitation tests eroded surface of the specimens has been observed by means of scanning electron microscopy. The roughness of the surface was measured on profile contact tester. The best resistance for cavitation erosion exhibited AlSi7Mg alloy after heat treatment, the weakest AlSi11Mg alloy in as-cast condition.

Abstract: The paper presents the results of research on surface condition of zinc coatings. Profilometric studies were performed for zinc coatings formed in industrial continuous hot-dip galvanization process and for the same coatings after two years of use. The results include the geometrical shape of 2D and 3D surfaces, distribution of vertices on the surface and roughness and waviness profiles. The parameters R_a, R_z, S_a and S_z were used to define the surface roughness. The study was conducted using FRT Microprof optical profilometer with data acquisition and analysis by MARK III software package.

Abstract: In this article, both the composition and composite properties of radioactive sources for medical applications are worked out and studied. The bases of these sources are bioinert ceramic solids and radionuclides. The active source is constituted from dispersed radioactive yttriа oxide or strontium oxide monolithically encapsulated with bioinert glass flux. The thermal expansion properties of the analyzed composites are highly similar to the ones of both titanium metal and titanum alloys. Therefore, the developed radioactive sources can be mounted on titanium holder. Importantly, all utilized elements and alloys are already applied in medicine. In this article we demonstrate the use of a radioactive β-source placed on a titanium holder. The device is finally applied in a oncological model disease treatment.

Abstract: The results obtained for the characterization of the surface texture of concrete protected by coal tar using a 3D-topographical approach are presented here. The concrete, which presents a low waterbinder ratio, high compressive strength, and high impermeability, has been subjected to an aggressive acidic environment by immersion in 2.5%H₂SO₄. The profilometry technique, which produces 3D-topographical images and amplitude parameters, is used to compare the coated and uncoated surface textures before and after chemical attack, to evaluate the degradation of concrete, and the minimization of such effect in the coated concrete. The degradation and the minimization of degradation can be confirmed by the variation in all the parameters studied. This research, based on studies of profilometric analyses, demonstrates the accuracy, precision and efficiency of this technique in analyzing the concrete surface, indicating that it can be broadly employed in concrete durability research. The methodology adopted demonstrates that the application of coal tar as a protective coating for concrete in an aggressive environment minimizes its surface degradation and increases its durability.

Abstract: The profilometry of three dimensional objectives based on phase approaching of projected grating is widely used in various fields of application engineering. In this paper, two cameras are equipped in our system to obtain fast and static measurement compared to the conventional measuring system with single camera which needs rotated measurement. Algorithm of phase unwrapping based on reliability is also adopted to improve the performance which avoid the breakage of projected grating. Experimental data indicates the measurement error of this Two-camera phase measuring profilimetry system is within 1%. This new profilometry system has great potential application value in the profile measurement of static three dimensional targets.