scholarly journals Failure analysis of a motor vehicle suspension helical spring

2020 ◽  
Vol 6 (1) ◽  
pp. 72-82
Author(s):  
Lidia Bohun ◽  
◽  
Eduard Pleshakov ◽  
Sergiy Shvachko ◽  
◽  
...  
Keyword(s):  
Protective Coating ◽  
Motor Vehicle ◽  
Protective Coatings ◽  
Safety Margin ◽  
Corrosion Damage ◽  
Metallographic Analysis ◽  
Crack Plane ◽  
Deep Pit ◽  
Metallic Inclusions ◽  
Spiral Surface

The purpose of this work is to reveal the cause of the failure of the motor vehicle rear suspension barrel-shaped spring with the progressive elasticity characteristic and predict measures to increase the lifetime of springs of this type. The fracture of the spring occurred on the middle coil, which operates under conditions of more severe stress in comparison with other coils. The chemical composition of the spring material, determined by X-ray fluorescence spectral and microstructural analyzes, corresponded to chromium-silicon steel 54SiCr6. In terms of structure and mechanical properties, the spring material met the standards. No traces of decarburization were detected, and no crack initiation, caused by non-metallic inclusions, was found in the material of the fractured spring. Macroscopic examination of the spring surface did not reveal any cracks, scratches, dents, traces of blows with stones and marks of spring coiling tool. Instead, extensive areas of exfoliation of the protective coating were found. The metallographic analysis revealed selective corrosion in the form of pitting damage in places of exfoliation of the protective coating. The fatigue crack propagates from the certain deep pit with the reorientation of the crack plane along the spiral surface to the central axis of the coil wire. After depletion of the safety margin, the spring broke down quickly. The fast fracture zone contains steps of the river pattern formed due to the spiral reorientation of the fracture surface. The research can be used to understand the importance of adhesive strength and wear resistance of protective coatings on the spring surface. Their local exfoliation causes subsequent corrosion damage to the spring, which stimulates its fatigue fracture.

Assessment of Damage from Organic Protective Coating Treatments to Historic Stone Buildings and Sculptures

2010 ◽  
Vol 44-47 ◽  
pp. 610-613
Author(s):  
Qiang Liu ◽  
Bing Jian Zhang
Keyword(s):  
Protective Coating ◽  
Side Effect ◽  
Protective Coatings ◽  
Organic Coating ◽  
Stone Conservation ◽  
Silicon Compounds ◽  
Artificial Weathering ◽  
Organic Silicon ◽  
Destruction Mechanism ◽  
Historic Stone

The conservation of historic stone buildings and sculptures is receiving growing attention because of weathering. Now, the techniques for stone conservation are primarily achieved through the use of organic coating treatments. Although some defects of organic protective materials have been recognized, the further shortcoming is still short of awareness. Here we show our investigations of the side effect of organic coating treatments. Some kinds of common stones, including sandstone, tuff, granite, dolomite and marble, were selected as protected objects. Organic silicon compounds were used as protective coatings. The artificial weathering, including salting, freezing and heating, was designed. The treated stones’ decaying was investigated. The results reveal that the treated stone decaying is aggravated. Moreover, the destruction mechanism has been discussed.

scholarly journals Deposition of SiOxCyHz Protective Coatings on Polymer Substrates in an Industrial-Scale PECVD Reactor

Coatings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 234 ◽  
Author(s):  
Žiga Gosar ◽  
Janez Kovač ◽  
Miran Mozetič ◽  
Gregor Primc ◽  
Alenka Vesel ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Protective Coating ◽  
Photoelectron Spectroscopy ◽  
Secondary Ion Mass Spectrometry ◽  
Protective Coatings ◽  
Plasma Reactor ◽  
Chemical Vapour ◽  
Rf Discharge ◽  
Average Roughness ◽  
Polymer Substrates

The deposition of protective coatings on aluminised polymer substrates by a plasma enhanced chemical vapour deposition PECVD technique in a plasma reactor with a volume of 5 m3 was studied. HMDSO was used as a precursor. Plasma was sustained in a capacitively coupled radiofrequency (RF) discharge powered by an RF generator operating at 40 kHz and having an adjustable output power up to 8 kW. Gaseous plasma was characterised by residual gas mass spectrometry and optical emission spectroscopy. Polymer samples with an average roughness of approximately 5 nm were mounted into the plasma reactor and subjected to a protocol for activation, metallisation and deposition of the protective coating. After depositing the protective coating, the samples were characterised by secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS). The combination of various techniques for plasma and coating characterisation provided insight into the complex gas-phase and surface reactions upon deposition of the protective coatings in the industrial-size plasma reactor.

scholarly journals The Key Construction Technology Research on the Intercontinental Shanghai Wonderland

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Peng Jiang ◽  
Shaole Yu ◽  
Wei Luan ◽  
Xinxi Chen ◽  
Yang Qin ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Safety Margin ◽  
Time History ◽  
Construction Technology ◽  
Construction Process ◽  
Component Size ◽  
Finite Element Software ◽  
Deep Pit ◽  
The Stability

The Intercontinental Shanghai Wonderland is the first natural ecological hotel built in an abandoned mine in the world, which faces many difficulties in the construction process. To solve the difficult problems in the construction process, the study was carried out from the stability analysis of the deep pit cliff, the mechanical performance of the structure, and the construction technology. The Intercontinental Shanghai Wonderland is built around the abandoned deep pit cliffs, and the stability of the deep pit cliffs directly affects the safety of the building. The dynamic response characteristics and the instability characteristics of the mine slope under the dynamic response were analyzed by a three-dimensional dynamic finite element method. The calculation results showed that with effective anchoring support measures, the stability coefficient of slope under static load and small earthquakes was large, which had a certain safety margin. Under the action of large earthquakes, the slope could still meet the stability requirements. The structure of the Intercontinental Shanghai Wonderland is a unique two-point support structure system. It shows the deformation and stress characteristics of one fixed end and one simply supported end under horizontal load. The elastic-plastic time history response of structures under actions of rare earthquakes was analyzed through the finite element analysis software. The analysis results show that the current structural system along with the design of component size and strength can meet the seismic performance of the structure under actions of rare earthquakes. The Intercontinental Shanghai Wonderland was built in a stone pit 88 m below the surface. Therefore, the transportation of materials was a difficulty in the construction process. A set of ultradeep concrete downward conveying equipment was invented to solve the difficulty. The construction process of the whole structure was simulated by finite element software, which provided a safety guarantee for the construction of the whole structure.

THE USE OF METALLOGRAPHIC ANALYSIS OF FRICTION LININGS IN THE BRAKING SYSTEM TO DETERMINE THE PROCESSES OF TRIBOLOGICAL WEAR

Tribologia ◽  
2018 ◽  
Vol 279 (3) ◽  
pp. 13-18
Author(s):  
Henryk BĄKOWSKI ◽  
Zbigniew STANIK ◽  
Bartosz CHMIELA
Keyword(s):  
Qualitative Analysis ◽  
Diagnostic Criteria ◽  
Wear Mechanisms ◽  
Motor Vehicle ◽  
Friction Pair ◽  
Operating Conditions ◽  
Metallographic Analysis ◽  
Technical Object ◽  
Service Employees ◽  
Braking System

The work presents metallographic examinations of worn brake linings under various operating conditions. The main purpose of this work is to determine the types of friction pair wear of braking systems under specific operating conditions. This is important for car service employees and appraisers who, based on quantitative and qualitative analysis, will determine the dominant mechanisms of wear. This is very important due to the possibility of determining the operating conditions, and thus the assessment of the use not only of the friction pair, but also the entire technical object, which is a motor vehicle. On the basis of the quantitative metallographic analysis of the research, individual wear mechanisms were presented, taking into account the determined diagnostic criteria during the measurement.

Nonmetallic inclusions in rails made of electro-steel alloyed with chromium

2020 ◽  
Vol 62 (12) ◽  
pp. 936-942 ◽  
Author(s):  
A. A. Umanskii ◽  
A. V. Golovatenko ◽  
A. S. Simachev
Keyword(s):  
Hot Deformation ◽  
Ultrasonic Testing ◽  
Nonmetallic Inclusions ◽  
Relative Concentration ◽  
Metallographic Analysis ◽  
High Ductility ◽  
High Concentration ◽  
Metallic Inclusions ◽  
Significant Concentration

Type, relative concentration and size of most characteristic non-metallic inclusions for the elements of rails (head, web) from electro-steel of E79KhF and E90KhАF grades were determined on the basis of metallographic (with a microscope “OLYMPUS GX-51”) and spectral (using spectrometer “ARL iSpark” method “Spark-DAT”) analyses. It was found that the highest relative concentration of manganese sulfides (MnS) is 30.8 – 43.4 ppm. At the same time, 60 – 100 % of inclusions of this type are of small sizes (less than 4 μm), and it does not allow them to be detected using standard metallographic analysis with 100-fold magnification. The revealed high relative concentration of sulfide inclusions directly correlates with the established positive sulfur liquation in considered rail elements, which is up to 40 %. Despite the high concentration of manganese sulfides, their influence on the quality of rails can be considered not dangerous, taking into account their high ductility during hot deformation and the established prevalence of inclusions of this type with small size (less than 4 μm). Among inclusions of a silicate type, SiO2 inclusions (3.4 – 14.9 ppm) have a significant concentration. All detected inclusions of this type have a size not exceeding 4 μm. It was found that the concentration of complex inclusions containing alumina (Al2O3 – CaO – MgO, Al2O3 – CaO – MgO – CaS, Al2O3 – CaO, Al2O3 – MgO) is insignificant: in total it does not exceed 3.1 ppm and 1.6 ppm for individual types. The concentration of corundum (Al2O3) is also insignificant and does not exceed 0.3 ppm. In this case, alumina inclusions of small size (less than 6 μm) prevail. Due to the low contamination (taking into account the relative concentration and size of inclusions) with non-plastic silicate and alumina non-metallic inclusions, their influence on the quality of the rails was not significant. It is confirmed by the absence of defects detected during ultrasonic testing.

scholarly journals Gas Evolution Rates of Graphite Protective Coatings in Dependence on the Applied Solvent and Kind of Atmosphere

2016 ◽  
Vol 61 (4) ◽  
pp. 2129-2134
Author(s):  
A. Kmita ◽  
D. Drożyński ◽  
J. Mocek ◽  
A. Roczniak ◽  
J. Zych ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Protective Coating ◽  
Protective Coatings ◽  
Measuring Method ◽  
Gas Evolution ◽  
Casting Method ◽  
Air Atmosphere ◽  
Two Systems ◽  
Mould Cavity

Abstract The results concerning emission of gases from two commercial graphite protective coatings for moulds and cores (water and alcoholic) are given in the hereby paper. Investigations were performed in two systems. One of the systems was corresponding to conditions occurring inside the mould cavity immediately after its pouring with liquid metal (Method 1), while the second was simulating conditions deep inside the mould at a certain distance from the casting (Method 2). Investigations were carried out in the CO2 atmosphere and in the air. The water protective coating generated 1.5 to 3 times larger volume of gases than the alcoholic coating (in dependence on the measuring method and atmosphere). The smallest differences occurred in the air atmosphere, while the largest in the CO2 atmosphere.

scholarly journals Comparative Evaluation of effect of resin protective coatings on the surface hardness and shear punch strength of different GlCs - An InVitro Study

2021 ◽  
Vol 19 (3) ◽  
pp. 160-165
Author(s):  
N. Mishra ◽  
M. Agarwal ◽  
M. P. Singh ◽  
A. Khullar ◽  
K. Magwa ◽  
...  
Keyword(s):  
Shear Strength ◽  
Clinical Practice ◽  
Protective Coating ◽  
Surface Coating ◽  
Comparative Evaluation ◽  
Protective Coatings ◽  
Surface Hardness ◽  
Daily Clinical Practice ◽  
Glass Ionomer ◽  
Shear Punch

G-Coat Plus is a nano-filled, self-adhesive light cured protective coating that strengthens, protects and enhances glass ionomer restorations. The effect of G- Coat plus on different GICs have not been studied comprehensively. Hence the study was conducted to compare the effect of resin coating on surface hardness and Shear punch strength of newer modified GIC.Materials and methods: 120 samples of three GICs i.e. Fuji IX Extra, Fuji IX Fast, Fuji II LC were prepared using specialized metal moulds. Specimens of Fuji II LC were light cured for 20 seconds. Coated and uncoated samples were tested for surface hardness and 30 samples were tested for shear punch strength. P < 0.05 was considered as significant. Results: Shear Punch Strength after G-Coat plus coating was significantly higher for Fuji IX Extra followed by Fuji II LC. Surface Hardness after G- Coat plus coating was significantly higher for Fuji IX Extra followed by Fuji IX Fast and Fuji II LC.Conclusion: Surface coating by a resin agent significantly increases the surface hardness and shear strength of the GIC. Considering the above stated findings, they can be incorporated into daily clinical practice to enhance the strength and longevity of GIC.

Protective Coating Based on Siloxane Polymer Nanopatterned by Alkoxytitanate

2019 ◽  
Vol 945 ◽  
pp. 718-723 ◽  
Author(s):  
V.Y. Chukhlanov ◽  
O.G. Selivanov ◽  
N.V. Chukhlanova
Keyword(s):  
Protective Coating ◽  
Negative Impact ◽  
Protective Coatings ◽  
Anthropogenic Factors ◽  
Adhesive Properties ◽  
Atomic Force ◽  
Surface Nanostructure ◽  
Siloxane Polymer ◽  
20 Nm ◽  
The Impact

The paper considers the problems of creating new protective coatings based on organosilicon polymer – polymethylphenylsiloxane, modified with tetraisopropyltitanate. The mechanisms of siloxane polymer nanostructuring have been suggested. The coating surface nanostructure and the impact of material components content and nature on its properties have been studied. To research protective surface nanostructure, the method of atomic-force probe microscopy applying IntegraAura device has been used. Nanoparticles formations with 10-20 nm effective scale have been revealed. Adhesive properties of the protective coating have been studied. Glass and metal adhesion was determined applying the method of detachment from the steel discs substrate using adhesive meter PSO-MG4. The modification was stated not to cause any substantial loss of coating adhesive properties. Simultaneously modification process was accompanied with the increase of relative coating firmness.The developed compounds and corresponding coatings are aimed at protecting buildings and constructions against negative impact of natural and anthropogenic factors.

Study of Corrosion Damage Under Protective Coatings

2001 ◽  
Author(s):  
Mohammad Khobaib ◽  
Jochen Hoffmann ◽  
Shamachary Sathish ◽  
Michael S. Donley
Keyword(s):  
Spatial Resolution ◽  
Electrochemical Impedance ◽  
Protective Coatings ◽  
Salt Spray ◽  
Electrochemical Techniques ◽  
Corrosion Damage ◽  
Acoustic Microscopy ◽  
Localized Corrosion ◽  
Corrosion Activity ◽  
Military Aircraft

Abstract Polymer coatings provide an excellent corrosion barrier for Al-skinned military aircraft. However, the degradation and damage of the coatings in their service life over time leads to the initiation of corrosion damage at the substrate level. Early detection and negation of such activity can provide extensive cost savings. Several Electrochemical techniques and Non Destructive Evaluation (NDE) show promise in detecting the onset of corrosion under such coatings. Current accelerated testing of aircraft coating systems for corrosion protection relies heavily on salt spray methods. Electrochemical techniques such as Electrochemical Impedance Spectroscopy (EIS) and Electrochemical Noise Methods (ENM) provide insight into the global properties of a coating system, and both techniques are being used on a limited basis. However, there is a need to investigate corrosion events with greater spatial resolution under coatings at the metal/coating interface. Such corrosion activity may be related to coating defects and variations in the surface chemistry of the underlying metal. The Scanning Vibrating Electrode Technique (SVET) has been developed to allow the investigation of localized corrosion activity with high spatial resolution. Such activity may be associated with coating defects or galvanic coupled regions of the metal surface. Electrochemical and NDE techniques were used to investigate the early stage of corrosion activity under protective coatings. Coatings in this investigation ranged from a simple epoxy amine to commercially used military aircraft polyurethane coatings. SVET testing of panels with intact high-resistance barrier coatings could not reveal corrosion damage under normal testing conditions because of little or no corrosion activity within the limited exposure time. Chemical, mechanical, and electrochemical means of accelerating the corrosion damage were utilized to obtain results in a reasonable time frame. Corrosion initiation and its progress under the coating were studied in detail and the results are discussed here. Complimentary high-resolution NDE techniques, such as Scanning Acoustic Microscopy (SAM) and Fan Thermography measurements were used to identify the corrosion sites. The overall objective of this investigation is to establish a correlation between the electrochemical and NDE techniques.

New Powdered Silicide Materials for Thermal Spraying Process and Coatings on the Niobium Base Alloys

1998 ◽  
Author(s):  
V. Terentieva ◽  
O. Bogatchkova ◽  
D. Cornu
Keyword(s):  
Protective Coating ◽  
Protective Coatings ◽  
Thermal Spraying ◽  
Base Material ◽  
Theory And Practice ◽  
Powder Materials ◽  
Self Healing ◽  
High Enthalpy ◽  
Boride Phases ◽  
Spraying Process

Abstract The given article presents some results of the scientific research devoted to the development of a new class of scale-resistant powder materials of the Si-Ti-Mo-B system for thermal spraying and using these materials for the creation of heat-resistant coatings on the niobium base alloys by means of various methods of thermal spraying. Also under consideration are problems relating to the theory and practice of obtaining reliable protective coatings on high-melting metals and their alloys, niobium ones included, intended for operation in high-enthalpy oxygen-containing gas flows. Hazard in commencing an oxidation reaction of the base material under coating is connected with density of open pores and cracks, and partial pressure of the oxidizer. Powdered multicomponent heterophase materials for gas-thermal spraying of protective coating with a self-healing ability and controlled properties are proposed. Finally the results of some properties of new silicide-type heterophase powders containing silicide and boride phases for a thermal spraying process and some properties of protective coating deposited on the niobium base alloys by means of a thermal spraying technique are presented.

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