scholarly journals The analysis of friction properties after laser texturizing of the silicon carbide surface layer

2018 ◽  
Vol 183 ◽  
pp. 02010
Author(s):  
Norbert Radek ◽  
Agnieszka Szczotok ◽  
Renata Dwornicka
Keyword(s):  
Silicon Carbide ◽  
Surface Layer ◽  
Statistical Analysis ◽  
Design Of Experiments ◽  
Laser Beam ◽  
High Reliability ◽  
Laser Beam Machining ◽  
Before And After ◽  
High Roughness ◽  
Modification Of The Surface

The modification of the surface properties is a desired technological procedure. One of the possible method is the electro-spark deposition (ESD). Unfortunately, ESD process produces a surface with high roughness. The laser beam machining (LBM) has been involved to lower roughness of the coating made by ESD. The elements coated by ESD have been tested to determine tribological properties and they were compared before and after LBM. To achieve high reliability of the results, the test has been conducted in accordance with design of experiments methodology and the results which were obtained have been processed by a statistical analysis. The description of such an experiment performed for a silicon carbide SiC coating, the obtained results and the conclusions are included in this paper.

The Average Friction Coefficient of Laser Textured Surfaces of Silicon Carbide Identified by RSM Methodology

2014 ◽  
Vol 874 ◽  
pp. 29-34 ◽  
Author(s):  
Norbert Radek ◽  
Jacek Pietraszek ◽  
Bogdan Antoszewski
Keyword(s):  
Silicon Carbide ◽  
Surface Layer ◽  
High Reliability ◽  
Hard Material ◽  
Textured Surfaces ◽  
Electrospark Deposition ◽  
Laser Beam Machining ◽  
Before And After ◽  
Cheap Method ◽  
High Roughness

The electrospark deposition (ESD) is a well-known cheap method utilizing concentrated energy flux to transfer a material of an electrode onto the surface of the machined material for enhancing properties of its surface layer. Typically, a hard material of an electrode may be deposited onto the surface of materials with lower hardness to make such an object more robust for wearing. Coatings produced by ESD may be applied to protect new elements or to recover the properties of worn elements. Unfortunately, ESD process produces a surface with high roughness. The laser beam machining (LBM) has been involved to lower roughness of the coating made by ESD. The elements coated by ESD have been tested to determine tribological properties and they were compared before and after LBM. To achieve high reliability of the results, the test has been conducted in accordance with design of experiments (DoE) methodology and the results which were obtained have been processed by a statistical analysis. The description of such an experiment performed for a silicon carbide SiC coating, the obtained results and the conclusions are included in this paper.

scholarly journals The Morphology and Mechanical Properties of ESD Coatings before and after Laser Beam Machining

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2331 ◽  
Author(s):  
Norbert Radek ◽  
Jacek Pietraszek ◽  
Aneta Gądek-Moszczak ◽  
Łukasz J. Orman ◽  
Agnieszka Szczotok
Keyword(s):  
Mechanical Properties ◽  
Laser Beam ◽  
Laser Processing ◽  
Temperature Fields ◽  
Rolling Stock ◽  
Laser Beam Machining ◽  
Laser Modification ◽  
Before And After ◽  
The Impact ◽  
Morphology And Mechanical Properties

Electro-spark deposition (ESD) and laser beam machining (LBM) are the technologies using the concentrated energy flux. This paper deals with the issue of the impact of laser modification on the morphology and mechanical properties of carbide/copper coatings produced by electro-spark treatment. The coatings were applied to C45 carbon steel samples using the EIL-8A device. The following three types of electrodes made using the powder metallurgy (PM) hot pressing technique, from copper and tungsten carbide powders of different percentage compositions, were used for the coatings: 25% WC and 75% Cu; 50% WC and 50% Cu; and 75% WC and 25% Cu. Laser modification of the surface layers was performed with an Nd:YAG laser. The research focused on the analysis of the morphology of coatings applied by electro-spark technology before and after laser processing. The analysis of the morphology of electro-spark coatings revealed that the coatings had microcracks and pores. The laser beam machining of ESD coatings led to the homogenization of chemical composition, fragmentation of the structure, and elimination of microcracks. In addition, measurements of porosity, microhardness, adhesion, and analysis of XRD phase composition of the electro-spark coatings were performed. Laser processing proved to have a positive effect on improving the adhesion of coatings and reducing their porosity. This paper also presents a simulation model of heat transfer processes for the case of laser radiation impact on a WC-Cu coating. The developed numerical model, describing the influence of laser treatment on the distribution of temperature fields in the heated material (at a given depth) is of significant importance in the development of treatment technologies. Laser-modified ESD coatings perform anti-wear and protective functions, which enable their potential application in means of transport such as rolling stock.

Analysis of responses on zirconium carbide based titanium using laser beam machining process

2021 ◽  
Author(s):  
Mahesh Mallampati ◽  
K. Somasundaram ◽  
J. Saranya ◽  
C. Harsha vardhan ◽  
V. Rakesh Kumar ◽  
...  
Keyword(s):  
Laser Beam ◽  
Zirconium Carbide ◽  
Machining Process ◽  
Laser Beam Machining

Reproducibility of velocity-dependent power: before and after lengthening contractions

2011 ◽  
Vol 36 (5) ◽  
pp. 626-633 ◽  
Author(s):  
Geoffrey A. Power ◽  
Brian H. Dalton ◽  
Charles L. Rice ◽  
Anthony A. Vandervoort
Keyword(s):  
Peak Power ◽  
High Reliability ◽  
Similar Amount ◽  
Shortening Velocity ◽  
Lengthening Contractions ◽  
Isokinetic Testing ◽  
Typical Error ◽  
Before And After ◽  
Absolute Reliability ◽  
Ankle Dorsiflexors

The determination of power using isokinetic testing has been shown to be highly reliable. However, isotonic and isokinetic testing involve specific mechanical constraints that likely necessitate different neuromuscular strategies. Therefore, the purpose here was to establish test–retest intrarater reliability (separated by 7 days) of loaded maximal shortening velocity and velocity-dependent power of the ankle dorsiflexors using the isotonic mode of the Biodex dynamometer (i) at baseline and (ii) throughout recovery following 150 high-intensity lengthening contractions. Intraclass correlation coefficients (ICC)2,1 with 95% CIs were used to determine relative reliability, whereas absolute reliability included typical error (TEM) and typical error expressed as a coefficient of variation (TEMCV). Twenty-four young men and women volunteered for the study. Maximal shortening velocity and power were determined with a fixed resistance set at 20% of maximal voluntary isometric contraction across 2 testing sessions separated by 7 days. ICCs were 0.93 and 0.98 for maximal shortening velocity and peak power, respectively. Following the lengthening contractions, ICCs indicated high reliability for maximal shortening velocity and peak power, 0.86 and 0.94, respectively, suggesting that a similar amount of fatigue was incurred on both days. Measures of absolute reliability for maximal shortening velocity and peak power also yielded high reliability. The isotonic mode is highly reliable when testing velocity-dependent power of the ankle dorsiflexors at baseline and following fatiguing lengthening contractions. The high reliability of this measure is encouraging and suggests that the isotonic mode can be used in various settings to track group changes before and after training and following fatigue and lengthening contractions.

Heat-Resistant Barrier Contacts Made on the Basis of TiBx and ZrBx to SiC and GaN

2009 ◽  
Vol 615-617 ◽  
pp. 565-568 ◽  
Author(s):  
Alexander A. Lebedev ◽  
A.E. Belyaev ◽  
N.S. Boltovets ◽  
V.N. Ivanov ◽  
Raisa V. Konakova ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Phase Composition ◽  
Heat Resistance ◽  
Contact Structure ◽  
Schottky Barriers ◽  
Electrophysical Properties ◽  
Depth Profiles ◽  
Contact Metallization ◽  
Before And After ◽  
Concentration Depth Profiles

We studied the heat resistance of AuTiBx (ZrBx) barrier contacts to n-SiC 6H and n-GaN. The Schottky barrier diode (SBD) parameters, the concentration depth profiles for contact structure components and the phase composition of contact metallization were measured both before and after rapid thermal annealing (RTA) at temperatures up to 900 °С (1000 °С) for contacts to GaN (SiC 6H). It is shown that the layered structure of metallization and electrophysical properties of Schottky barriers (SBs) remain stable after RTA, thus indicating their heat resistance. The ideality factor n of the I-V characteristic of SBDs after RTA was 1.2, while the SB height φВ was ~0.9 eV (~0.8 eV) for the gallium nitride (silicon carbide) barrier structures.

Impact of Legislation on Opioid Prescribing following Hysterectomy and Hysteroscopy in Arizona and Florida

2021 ◽  
pp. 1-9
Author(s):  
Aakriti R. Carrubba ◽  
Amy E. Glasgow ◽  
Elizabeth B. Habermann ◽  
Amanda P. Stanton ◽  
Megan N. Wasson ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Cohort Analysis ◽  
Oral Morphine ◽  
Interrupted Time Series ◽  
Interrupted Time Series Analysis ◽  
Opioid Use ◽  
Prescribing Practices ◽  
Opioid Prescribing ◽  
Before And After ◽  
Legislative Changes

<b><i>Objectives:</i></b> This study aimed to determine the oral morphine equivalents (OMEs) prescribed and refill rates following hysterectomy and hysteroscopy in the setting of opioid prescribing practice changes in 2 states. <b><i>Design:</i></b> This is a retrospective cohort analysis consisting of 2,916 patients undergoing hysterectomy or hysteroscopy between July 2016 and September 2019 at 2 affiliated academic hospitals in states that underwent legislative changes in opioid prescribing in 2018. <b><i>Methods:</i></b> Participants were identified using the Current Procedural Terminology procedure codes in Arizona and Florida. Hysterectomy was chosen as the most invasive gynecologic procedure, while hysteroscopy was chosen as the least invasive. Medical records were abstracted to find opioid prescriptions from 90 days before surgery to 30 days after discharge. Patients with opioid use between 90 and 7 days before surgery were excluded. Prescriptions were converted to OMEs and were calculated per quarter year. Statistical analysis included Wilcoxon rank sum <i>t</i> tests for OMEs and χ<sup>2</sup> <i>t</i> tests for refill rates. Interrupted time-series analysis was used to determine significant change in OMEs before and after legislative change. Statistical analysis was performed using SAS version 9.4 (SAS Institute, Cary, NC, USA). <b><i>Results:</i></b> In Arizona, 1,067 hysterectomies were performed; 459 (43%) vaginal, 561 (52.6%) laparoscopic/robotic, and 47 (4.4%) abdominal. There were 530 hysteroscopies. Overall median OMEs decreased from 225 prior to July 2018 to 75 after July 2018 (<i>p</i> &#x3c; 0.0001). The opioid refill rate remained unchanged at 7.4% (<i>p</i> = 0.966). In Florida, there were 769 hysterectomies; 241 (31.3%) vaginal, 476 (61.9%) laparoscopic/robotic, and 52 (6.8%) abdominal. There were 549 hysteroscopies. Overall median OMEs decreased from 150 prior to July 2018 to 0 after July 2018 (<i>p</i> &#x3c; 0.0001). The opioid refill rate was similar (7.8% before July 2018 and 7.3% after July 2018; <i>p</i> = 0.739). <b><i>Limitations:</i></b> Limitations include involvement of a single hospital institution with a total of 10 fellowship-trained surgeons and biases inherent to retrospective study design. <b><i>Conclusions:</i></b> Legislative and provider-led changes coincided with decreases in opioid prescribing after 2018 in both states without increasing rates of refills and showed actual data reflected in the medical record. Gynecologists must actively participate in safe prescribing practices to decrease opioid dependence and misuse.

Damage in High Energy Light Ions Irradiated Silicon Carbide

1998 ◽  
Vol 510 ◽  
Author(s):  
P. Leveque ◽  
S. Godey ◽  
P.O. Renault ◽  
E. Ntsoenzok ◽  
J.F. Barbot
Keyword(s):  
Silicon Carbide ◽  
Surface Layer ◽  
Energy Transfer ◽  
High Energy ◽  
Alpha Particles ◽  
Defect Production ◽  
Majority Carrier ◽  
Reflectivity Spectra ◽  
Light Ions ◽  
Compensation Layer

AbstractCommercial n-type 4H-SiC wafers were implanted with doses of MeV alpha particles, high enough to cause majority carrier modification. Analysis of infrared reflectivity spectra shows that the implanted crystals can be divided into three layers: a surface layer of about 30 nm followed by a compensation layer where the energy transfer of the incident particles is low and an overdoping layer in the region of maximum defect production, i.e. near the theoretical mean range of ions Rp

scholarly journals Statistical Analysis using traditional technique, Microsoft Excel and Predictive Analytic Software

10.17158/514 ◽  
2016 ◽  
Vol 19 (2) ◽  
Author(s):  
Jovelyn M. Durango ◽  
Carlito P. Yurango
Keyword(s):  
Statistical Analysis ◽  
Completion Time ◽  
Microsoft Excel ◽  
Instructional Tools ◽  
Traditional Technique ◽  
Significant Difference ◽  
Before And After ◽  
Computer Based ◽  
The One ◽  
Time Required

<p>The advent of technology has improved the way statistics is taught and learned. It is claimed that the use of computer-based instructional tools can actively explore the meaning of statistical concepts among the students, as well as enhance their learning experiences. This study aimed to compare three methods of statistical analysis namely, the traditional technique (use of the calculator), Microsoft Excel and Statistical Package for Social Sciences (SPSS) software. This investigation utilized the experimental design, specifically the One-Group Pretest – Posttest Design. There were six education students who self-assessed their attitude before and after the introduction of the use of various computation techniques and performed the statistical analysis considering also the completion time required for each process. Results of the study revealed an increase in the level of attitude among the respondents form the pretest to the posttest. Also, the cognitive level regardless of the approach was very high. However, the t-test failed to establish a significant difference in the attitude among the respondents. On the other hand, there were significant differences in both the test scores and completion time of the respondents in the three methods in favor of SPSS.</p><p> </p><p><strong>Keywords: </strong>Information technology, statistics, traditional technique, Microsoft excel, SPSS, comparative analysis, experimental research design, Davao City, Philippines. </p>

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