Examining properties of arc sprayed nanostructured coatings

The article presents the results of examining properties of arc sprayed coating obtained with nano-alloy on the iron matrix with a high amount of fine carbide precipitates sprayed on non-alloyed steel plates intended for high temperature operation. Powder metal cored wire EnDOtec DO*390N 1,6 mm diameter, was used to produce, dense, very high abrasion and erosion resistant coatings approx. 1,0 mm thick. Nano-material coatings characterization was done to determine abrasion resistance, erosion resistance, adhesion strength, hardness as well as metallographic examinations. Results have proved high properties of arc sprayed nano-material coatings and have shown promising industrial applications

Analysis of images recorded during welding processes,

Abstract In the paper elements of a system of assessment of a welding process and welded joints have been presented. The system was based on the application of one thermovision and two CCD cameras. In the paper exemplary results of processing and analysis of thermal and ordinary images have been discussed. Introduction The course of a welding process significantly influences the quality of welds. In order to obtain high quality joints proper parameters of welding process are required to be stable. In most cases by a correct welded joints one assumes the joints which are characterized not only by required mechanical properties but also by aesthetic quality. While the selection of proper welding parameters for an experienced welder does not make difficulties, the stability of these parameters is often not easy to be ensured. Abnormality of the process is caused by numerous factors which are often random. Examples are instability of passing of a filler wire, smudges of dirt, inaccuracy of preparation of element edges, deformations of elements as effects of thermal phenomena. These factors are reasons of common welding defects, such as excessive undercuts, partial or lack of joint penetration, cracks, overheatings, excessive convexity or concavity of a face of weld, blisters, bubbles and holes Maintenance of the high quality welding process and welds can be obtained by means of constant control of process parameters. One describes different approaches to the process inspection. Examples are measurements of amperage, voltage and flow of shielding gas The main problem concerning the application of vision systems seems to be a proper image analysis. In welding industry methods based on image analysis are being used for seam tracking Issues described in the paper are a part of investigations aimed at development of a system of controlling automatic welding processes. According to this approach, the vision system consists of three cameras. A crucial role is played be an IR camera, which observes a welding arc and pool, and the joint that is getting cold. Observation of the process is also aided by two CCD cameras, which record correspondingly images representing the arc and the joint. There are two goals of image analysis. The first one is to asses the stability of welding process, which is performed by means of determination of geometrical parameters of the arc. Secondly, some common defects of joints are supposed to be detected. It should be stressed that the application of IR camera lets us to detect not only surface defects but also defects and phenomena that do not manifest themselves on the surface. Presented experiments were carried out with the use of series of samples divided into some groups characterized by: correctly prepared surface, surface covered with rust, and parts covered with some impurities Overview of the vision system The welding process can be realized with the use of different devices. In industrial production automated and equipped with robots stands are commonly used, they enable MIG or MAG welding. Usually in such automated processes elements to be joined move and a welding device passing the filled wire is motionless. The vision system elaborated within the framework of the research described in the paper has been assigned to such processes. General overview of the system was presented in figure 1. The system let us to record, archive, process, analyze and recognize two types of images acquired by three presented cameras: -hot area that includes sub-areas of arc, metal in fluid and solidification phases and welded elements, -self-cooling area consisting of weld and welded elements sub-areas. The system has included hardware and software part

Synthesis and Properties of High Tilted Antiferroelectric Esters with Partially Fluorinated Alkoxyalkoxy Terminal Chains

Novel chiral esters with partially fluorinated alkoxyalkoxy terminal chains are described. Their phase transition temperatures, enthalpies, and electrooptical properties are reported. A helical pitch in pure compounds and their mixtures based on selective reflection of light is also characterized

The properties of thermal sprayed aluminium coatings on non-alloy structural steel

Purpose: of this paper was comparison of the structure, hardness and erosive wear of aluminium coatings produced on non-alloy structural steel S355JR (EN 10025-2) using the powder flame spraying and wire arc spraying methods. Design/methodology/approach: The latest model of flame powder sprayer and wire arc sprayer was used in the experiments. This provided very reliable spraying conditions. The additional material for flame-spraying was of Metco 54NS-1 pure aluminium powder (EN AW 1100 series). In the arc spraying process the Metco Aluminium (EN AW 1100 series) 1.6 mm diameter pure aluminium thermal spray wire was used. In each spraying technology binding alloy, i.e. Ni-Al, was employed as a primer coating. The used spray processes produced dense, abrasion and erosion resistant coatings approximal 1.0 mm thick. Aluminium coatings were characterized in accordance with ASTM G 76-95 erosion resistance tests, ASTM C 633-01 adhesion strength, HV 0.1 hardness tests and metallographic analyses. The scope of research included: preparation material for spraying, selection of properly process parameters for each sprayed technique based on preliminary technological tests, coatings manufacturing, examining the structure and tribological properties of aluminium coatings, comparison of obtained samples. Findings: The obtained results have proven superior properties of arc sprayed aluminium material coatings and have shown to be promising in industrial applications. Research limitations/implications: The presented test results are a preliminary assessment of the properties of thermally sprayed aluminium coatings. Therefore, further research is required regarding the resistance of aluminium coatings to abrasion and corrosion. Practical implications: The study is focused on selecting the best and most economical technique for manufacturing of wear and corrosion resistance aluminium coatings with a thickness of approximately 1 mm. Originality/value: It has been demonstrated that the use of a Ni-Al primer coating improves the adhesion of flame and arc sprayed aluminium coatings to steel surfaces

Properties and Structure of Nanocrystalline Layers Obtained by Manual Metal Arc Welding (MMA)

The present paper is the result of the investigations of the properties and structure of nanocrystalline layers deposited from iron-based nanoalloy on steel S355N substrate by manual metal arc welding method (MMA). In the process of welding a 100 A current intensity was used with desiccation preheating at 80°C while maintaining the interpass temperature at range of 200°C. The resultant deposit welds were subjected to macro and microscopic metallographic examination, X-ray phase analyses and crystallite size was analyzed by X-ray diffractometry (XRD), additionally EDX chemical composition analysis of precipitates during scanning electron microscopy was performed. Working properties of the obtained nanocrystalline deposit welds were evaluated based on hardness and metal-to-mineral abrasive wear. The results of the deposit welds working properties measurements were compared with the properties of wear resistant steel HARDOX 400 type used as the reference material