A possibility of application of MTDIL to the Residual stresses analysis

The work demonstrates a proof of application of the modulated-temperature dilatometry (MTDIL) to the stresses investigations of the well known and commonly used hard coatings e.g. TiN, TiCN, TiAlN thin films deposited mainly on different type of tools for its higher performances. In the PVD (physical vapour deposition) processes such kind of coatings are formed in meta stable state caused, between other, by strong stresses between coating and substrate. These stresses have an important influence on the fundamental properties of the coatings, for example, adherence to the substrate, so they are the subject of many investigations by use of different methods, mainly XRD (X-ray diffraction). For the purpose of presentation of application of MTDIL for such kind of investigation two reference substrate materials were chosen: ARMCO steel and cemented carbide in the form suitable for dilatometric analysis covered, by actually the most conventional, TiN hard coating. In the article the experimental results are presented, discussed and compared with simple model formed by means of finite elements method (FEM). This revised version was published online in July 2006 with corrections to the Cover Date.     

Thickness determination of TiN and TiAl coatings on steel substrates using X‐ray diffraction method and their composition measurements by GD‐OES

This paper presents a nondestructive X‐ray diffraction method for the accurate determination of thicknesses of polycrystalline TiN and amorphous‐like TiAl coatings deposited by DC magnetron sputtering onto thick polycrystalline stainless steel and carbon steel substrates. This method relies on the measurement of intensity loss of a substrate reflection caused by the deposition of the coating. The uncertainty of the thickness measurements by the X‐ray diffraction depends on the mass absorption coefficient of the coating material and the quality of the collected diffraction patterns. For the coatings considered, thicknesses determined by the X‐ray diffraction method show very good agreement with the thickness values measured by scanning electron microscopy and ball crater techniques.     

Quality issues in proficiency testing

 Proficiency testing is a means of assessing the ability of laboratories to competently perform specific tests and/or measurements. It supplements a laboratory's own internal quality control procedure by providing an additional external audit of their testing capability and provides laboratories with a sound basis for continuous improvement. It is also a means towards achieving comparability of measurement between laboratories. Participation is one of the few ways in which a laboratory can compare its performance with that of other laboratories. Good performance in proficiency testing schemes provides independent evidence and hence reassurance to the laboratory and its clients that its procedures, test methods and other laboratory operations are under control. For test results to have any credibility, they must be traceable to a standard of measurement, preferably in terms of SI units, and must be accompanied by a statement of uncertainty. Analytical chemists are coming to realise that this is just as true in their field as it is for physical measurements, and applies equally to proficiency testing results and laboratory test reports. Recent approaches toward ensuring the quality and comparability of proficiency testing schemes and the means of evaluating proficiency test results are described. These have led to the drafting of guidelines and subsequently to the development of international requirements for the competence of scheme providers. Received: 2 January 1999 · Accepted: 7 April 1999     

玩具油漆涂层中有机锡检测能力验证样品研制及应用分析

制备了用于可迁移有机锡检测能力验证的玩具油漆涂层样品,并开展了相关测定能力验证计划,采用迭代法、四分位法和敏感分析法3种不同统计方法对23家实验室数据进行统计分析,并对不满意结果的原因进行了分析。结果表明所研制样品的均匀性和稳定性良好,能满足能力验证要求。不同统计方法对实验室能力评定结果存在差异,但指定值差异很小,而能力评定标准差差异较大,运用卡方检验能选择出更合理的统计方法。     

Detection of genetic modification in cured tobacco leaf: proficiency testing using polymerase chain reaction-based methods

The Cooperation Centre for Scientific Research Relative to Tobacco (CORESTA; Paris, France) "Task Force Genetically Modified Tobacco-Detection Methods" investigated the performance of qualitative and quantitative methods based on the polymerase chain reaction (PCR) for the detection and quantitation of genetically modified (GM) tobacco. In the 4 successful rounds of proficiency testing, the cauliflower mosaic virus 35S RNA promoter (CaMV 35S) and the Agrobacterium tumefaciens nopaline synthase terminator (NOS) were selected as target sequences. Blind-coded reference materials containing from 0.1 to 5.0% and from 0.15 to 4% GM tobacco were used in 2 rounds of qualitative and quantitative PCR, respectively. Eighteen laboratories from 10 countries participated in this study. Considering all methods and 2 rounds, the different laboratories were able to detect GM tobacco at the 0.1% level in 46 out of 58 tests in qualitative assays. The results of the proficiency test indicate that both end point screening and real-time quantitative methods are suitable for the detection of genetically modified organisms in tobacco leaf samples having a GM content of 0.1% or higher. The CORESTA proficiency study represents a first step towards the interlaboratory evaluation of accuracy and precision of PCR-based GM tobacco detection, which may lead to the harmonization of analytical procedures and to the enhancement of comparability of testing results produced by different laboratories.     

Quality assurance and quality control in forest soil analyses: a comparison between European soil laboratories

In transnational monitoring programmes, a balance between international reference methods, which improve spatial comparability, and national analysis methods that favour temporal comparability, by their use and testing over many years, needs to be sought. Prior to the next Pan-European Forest Soil Survey, a third interlaboratory comparison of soil analysis methods was organised. All participating laboratories were requested to use the same reference methods. Fifty-two soil laboratories from 27 European countries analysed a total of 48 soil parameters on three soil samples which were typical for European forest soils. The results of the statistical analysis showed a high interlaboratory and intralaboratory variability, especially for the acid oxalate extractions, particle size distribution, exchangeable elements and total carbonates. The intercomparability of the test results did not improve compared to the previous ring test. As the exercise aimed primarily at comparing the performance of the laboratories, it was not powerful enough to find cause–effect relationships between the meta information provided by the laboratories and the variability of the test results.     

Quality assurance and quality control in forest soil analyses: a comparison between European soil laboratories

In transnational monitoring programmes, a balance between international reference methods, which improve spatial comparability, and national analysis methods that favour temporal comparability, by their use and testing over many years, needs to be sought. Prior to the next Pan-European Forest Soil Survey, a third interlaboratory comparison of soil analysis methods was organised. All participating laboratories were requested to use the same reference methods. Fifty-two soil laboratories from 27 European countries analysed a total of 48 soil parameters on three soil samples which were typical for European forest soils. The results of the statistical analysis showed a high interlaboratory and intralaboratory variability, especially for the acid oxalate extractions, particle size distribution, exchangeable elements and total carbonates. The intercomparability of the test results did not improve compared to the previous ring test. As the exercise aimed primarily at comparing the performance of the laboratories, it was not powerful enough to find cause–effect relationships between the meta information provided by the laboratories and the variability of the test results.

     

Thermal degradation and fire performance of intumescent silicone‐based coatings

This paper deals with the thermal degradation and fire performance of silicone‐based coatings for protecting steel. In this study, the fire performance of silicone coatings as virgin or formulated materials is evaluated using two homemade fire testing methodologies: one similar to the “torch test” fire testing method and the other using a heat radiator test. It was shown that the performance of the silicone‐based coating used as thermal barrier can be improved incorporating a modifier (a mixture of polydimethylsiloxane and silica coated by a silane). In this case, silicone‐based coating swells and exhibits same fire performance as commercial intumescent coating at the torch test. It is shown that the incorporation of modifier in the silicone makes it to swell upon heating resulting in the formation of expanded material exhibiting low heat conductivity. Thermal degradation of the coating is also investigated: it occurs in three main steps leading to the formation of a tridimensional network characterized by the formation of Q⁴ structure at high temperature. Copyright © 2012 John Wiley & Sons, Ltd.     

Collaborative study for the quality control of trace element determinations in paint coatings Part 1. Interlaboratory study

Since the adoption of the European Standard EN71: Part 3 on toy safety, there has been dissatisfaction with the poor reproducibility obtained between laboratories using the test method for the determination of the migration of certain elements from paints to toys. This lack of quality control could result in toys being judged unacceptable with regard to the requirements of the EC Directive 88/378/EEC, which creates a potential barrier to trade. In order to improve the methods of measurements and testing, the Standards, Measurements and Testing Programme (SM&T) is currently supporting a project of which the final aim is to produce paint reference materials. The first step of this collaborative project is aimed to assess and possibly improve the state-of-the-art of trace element determinations in paint coatings through an interlaboratory study, the results of which are presented in this paper.     

Comparative evaluation of two quantitative test methods for determining the efficacy of liquid sporicides and sterilants on a hard surface: a precollaborative study

Two quantitative carrier-based test methods for determining the efficacy of liquid sporicides and sterilants on a hard surface, the Standard Quantitative Carrier Test Method-ASTM E 2111-00 and an adaptation of a quantitative micro-method as reported by Sagripanti and Bonifacino, were compared in this study. The methods were selected based on their desirable characteristics (e.g., well-developed protocol, previous use with spores, fully quantitative, and use of readily available equipment) for testing liquid sporicides and sterilants on a hard surface. In this paper, the Sagripanti-Bonifacino procedure is referred to as the Three Step Method (TSM). AOAC Official Method 966.04 was included in this study as a reference method. Three laboratories participated in the evaluation. Three chemical treatments were tested: (1) 3000 ppm sodium hypochlorite with pH adjusted to 7.0, (2) a hydrogen peroxide/peroxyacetic acid product, and (3) 3000 ppm sodium hypochlorite with pH unadjusted (pH of approximately 10.0). A fourth treatment, 6000 ppm sodium hypochlorite solution with pH adjusted to 7.0, was included only for Method 966.04 as a positive control (high level of efficacy). The contact time was 10 min for all chemical treatments except the 6000 ppm sodium hypochlorite treatment which was tested at 30 min. Each chemical treatment was tested 3 times using each of the methods. Only 2 of the laboratories performed the AOAC method. Method performance was assessed by the within-laboratory variance, between-laboratory variance, and total variance associated with the log reduction (LR) estimates generated by each quantitative method. The quantitative methods performed similarly, and the LR values generated by each method were not statistically different for the 3 treatments evaluated. Based on feedback from the participating laboratories, compared to the TSM, ASTM E 2111-00 was more resource demanding and required more set-up time. The logistical and resource concerns identified for ASTM E 2111-00 were largely associated with the filtration process and counting bacterial colonies on filters. Thus, the TSM was determined to be the most suitable method.     

The BIOREMA project—part 3: International interlaboratory comparison for bio-ethanol test methods

The main objective of the reference materials for biofuel specifications (BIOREMA) project is the development of two test materials (one bio-ethanol material and one biodiesel material) with well-established reference values. Of a series of three papers, this part describes the material preparation, homogeneity study, stability study, and characterisation of the bio-ethanol material. The test material thus obtained was used in an interlaboratory comparison (ILC) to assess current practices and comparability amongst laboratories providing bio-ethanol testing services. Only 13 participants provided data, resulting in a small dataset for evaluation. Further, it appeared that for a number of laboratories, there was not sufficient material for the determination of all requested parameters. In most cases, as far as the data permit, it can be concluded that the consensus values (based on participant’s results) are in good agreement with the reference or the BIOREMA values (obtained by NMIs participating in the project). For three parameters, namely ethanol content, water content, and density, there is good agreement between the reference and consensus values. For these parameters, the reproducibility standard deviation is close to, or even smaller than, the expanded uncertainty associated with the reference value. A number of parameters show very poor reproducibility, for example, pH_e, electrolytic conductivity, and acidity. The same applies to sodium and copper content, which are very low and therefore challenging parameters to measure accurately. The results of the ILC underpin the need for certified reference materials and demonstrate the requirement for more robust quality control to improve the precision and trueness of the results from testing laboratories.     

Evaluation of the Anticorrosive Behaviour of Organic Coatings by Using a Variant of Electrochemical Impedance Spectroscopy

 Electrochemical impedance spectroscopy (EIS) has been acknowledged as a modern and efficient method in the evaluation of the anticorrosive behaviour of coatings. However, difficulties in the interpretation of the complex experimental data present a significant drawback in the use of the method in field studies where quick results are required. The breakpoint frequency method is an extension of the basic EIS method, which allows rapid qualitative assessment of the condition of a coating. By the breakpoint frequency method, the behaviour of epoxy coatings containing various types of reinforcement and applied on steel specimens has been examined after long-term (up to 300 days) exposure to a corrosive environment. The parameter values obtained by the breakpoint frequency method, such as the delaminated area, have been compared with those obtained from fitting the experimental EIS data to a suitable equivalent circuit. These results have also been compared with those of the water permeability of free membranes and the diffusion coefficient determined by standard test methods (e.g. the cup test).     

Interlaboratory comparison of test results of an ordinal or nominal binary property: analysis of variation

Applications of a new statistical method Ordinal Analysis of Variance (ORDANOVA) for interlaboratory comparisons of measurement or test results of semi-quantitative (ordinal) and qualitative (binary) properties are discussed. ORDANOVA can be helpful for validation of measurement or test methods, proficiency testing of laboratories, development of reference materials with certified semi-quantitative and qualitative properties, that is, probably in every field where ANOVA is applied for quantitative properties. A statistics and criteria are proposed for performance assessment of laboratories active in semi-quantitative and qualitative testing and for other purposes of statistical analysis of such test results.     

X-ray photoelectron and scanning Auger electron spectroscopy study of electrodeposited ZnCr coatings on steel

Zn–Cr alloyed coatings electrochemically deposited are of high interest for leading steel manufacturing companies because of their novel properties and high corrosion resistance compared with conventional Zn coatings on steel. For tuning and optimizing the properties of the electrodeposited Zn–Cr coatings, a broad range of the deposition conditions must be studied. For this reason, two different types of material were investigated in this study, one with a low electrolyte temperature and one with an elevated electrolyte pH, compared with the standard values. Because different corrosion performance and delamination behaviour of the layers were observed for the two types, advanced surface analysis was conducted to understand the origin of this behaviour and to discover differences in the formation of the coatings. The topmost surface, the shallow subsurface region, and the whole bulk down to the coating–steel interface surface were analysed in detail by X-ray photoelectron spectroscopy (XPS) and high-resolution scanning Auger electron spectroscopy to determine the elemental and the chemical composition. For better understanding of the resulting layer structure, multiple reference samples and materials were measured and their Auger and XPS spectra were fitted to the experimental data. The results showed that one coating type is composed of metallic Zn and Cr, with oxide residing only on the surface and interface, whereas the other type contains significant amounts of Zn and Cr oxides throughout the whole coating thickness.     

Local comparability of proficiency testing results: determination of concrete slump and compressive strength values

A proficiency testing (PT) scheme is developed for comparability assessment of results of concrete slump and compressive strength determination. The scheme is based on preparing of a test portion/sample of a concrete in-house reference material (IHRM) at a reference laboratory (RL) in the same conditions for every PT participant. Therefore, in this scheme IHRM instability is not relevant as a source of measurement/test uncertainty, while intra- and between-samples inhomogeneity parameters are evaluated using the results of RL testing of the samples taken at the beginning, the middle and the end of the PT experiment. The IHRM assigned slump and compressive strength values are calculated as averaged RL results. Their uncertainties include the measurement/test uncertainty components and the components arising from the material inhomogeneity. The test results of 25 PT participants were compared with the IHRM assigned values taking into account both the uncertainties of the assigned values and the measurement/test uncertainties of the participants. Since traceability of the IHRM assigned values to the international measurement standards and SI units cannot be stated, local comparability of the results is assessed. It is shown, that comparability of the slump and compressive strength determination results is satisfactory, while uncertainty evaluation for slump results requires additional efforts.     

Tribological evaluation of HVOF thermal‐spray coatings as a hard chrome replacement

Hard chrome plating has been used in several different applications in industries that require abrasive sliding wear resistance, such as hydraulic pistons, shafts or bearings. However, the increasing environmental and worker safety pressures on electrolytic hard chrome are leading companies to adopt alternatives. The improvements of the high‐velocity‐oxy‐fuel (HVOF) thermal spray process allow the chromium coating replacement with a comparable or superior surface treatment and are more environmentally friendly. This HVOF process, as a flexible dry‐coating technology, avoids high‐volume waste streams and enables a flexible choice of coating material for each application. The cobalt–chromium‐cemented tungsten carbides are some of the easiest materials to spray and the WC‐10Co‐4Cr coatings have demonstrated superior performance over hard chrome with regard to mechanical and tribological properties. In this work, this coating has been deposited with a Sulzer Metco WokaJet‐400 kerosene fuel spray gun, and the spray conditions have been optimized in order to ensure the best properties of the coatings. The mechanical and tribological properties have been evaluated in coatings sprayed with four deposition conditions that involve different gas flow rates. The most wear‐resistant coating is obtained with those HVOF parameters that prevent decarburization of WC particles and, at the same time, allow an adequate agglomerate melting giving a good intersplat adhesion. The results indicate that HVOF‐sprayed WC‐CoCr coatings are a reliable alternative to electrolytic hard chrome (EHC) in the aeronautical industry to coat landing gear components. In particular, in the dry wear tests, the WC‐CoCr coatings outperform hard chrome coatings in wear resistance. Copyright © 2010 John Wiley & Sons, Ltd.     

An inter-laboratory comparison study for the determination of copper and lead from the wastewater of printed circuit board manufacturing industry in Pakistan

This inter-laboratory comparison study was arranged for 28 laboratories from different public and private sector organizations in Pakistan having wastewater testing capabilities aimed at improving the quality and comparability of test results. This national inter-laboratory study was started in December 2003 and completed in July 2004. Laboratories were invited to analyze the wastewater collected from printed circuit board (PCB) industry for lead and copper contamination. The samples fulfill the criteria for homogeneity and stability as done by the reference laboratory. The results obtained from participating laboratories were analyzed in terms of Hampel Test for outliers, while the performance evaluation of the participating laboratories was done on the basis of Z-score. An assigned value derived from the participant's results was compared with a reference value provided by a reference laboratory. Overall >50% of the participating laboratories have shown good performance in this PT-program     

Bias analysis of proficiency testing programme results

A proficiency testing programme might involve a great number of participating laboratories coming from different countries or regions, and normally they analysed the same test materials using their own routine analytical methods. Hence, the results of a proficiency testing programme may contain valuable information which could serve purposes other than just performance evaluation. This study attempted to extract information from the results of a proficiency testing programme for the purposes of educating the participating laboratories as suggested by ISO/IEC 17043. The “bias analysis” approach introduced in this study was based on the statistical model of measurement and the nature of bias in chemical analysis. With this approach, the participating laboratories could estimate the bias associated with different settings of experimental conditions according to the statistics of subset distribution of the reported results from the participating laboratories. This would be useful for them to review the analytical procedures they used and modify their methods if needed. The approach was applied to the analysis of data obtained from a number of past proficiency testing programmes, and the findings were discussed in this paper.     

Development of combinatorial chemistry methods for coatings: high-throughput adhesion evaluation and scale-up of combinatorial leads

Coupling of combinatorial chemistry methods with high-throughput (HT) performance testing and measurements of resulting properties has provided a powerful set of tools for the 10-fold accelerated discovery of new high-performance coating materials for automotive applications. Our approach replaces labor-intensive steps with automated systems for evaluation of adhesion of 8 x 6 arrays of coating elements that are discretely deposited on a single 9 x 12 cm plastic substrate. Performance of coatings is evaluated with respect to their resistance to adhesion loss, because this parameter is one of the primary considerations in end-use automotive applications. Our HT adhesion evaluation provides previously unavailable capabilities of high speed and reproducibility of testing by using a robotic automation, an expanded range of types of tested coatings by using the coating tagging strategy, and an improved quantitation by using high signal-to-noise automatic imaging. Upon testing, the coatings undergo changes that are impossible to quantitatively predict using existing knowledge. Using our HT methodology, we have developed several coatings leads. These HT screening results for the best coating compositions have been validated on the traditional scales of coating formulation and adhesion loss testing. These validation results have confirmed the superb performance of combinatorially developed coatings over conventional coatings on the traditional scale.     

Zinc coatings for oxidation protection of ferrous substrates

The oxidation resistance of ferrous materials at elevated temperatures is limited. For that purpose the performance of zinc coatings deposited with hot-dip galvanizing, pack cementation and thermal spraying was considered. In the present work the oxidation resistance of these coatings at 400°C was estimated with light microscopy, thermogravimetric analysis and X-ray diffraction. From this examination it was deduced that in every coating a scale that was mainly composed of ZnO was formed, while Fe oxides were also detected in galvanized and pack coatings. However, the presence of the Fe/Zn phases inside the galvanized and pack coatings led to the formation of cracks, which could expose the substrate and thus destabilize the coating. This phenomenon was not observed in the thermal sprayed coatings, where the Fe/Zn phases were absent. In any case these cracks are not likely to jeopardize the resistance of the coating because zinc is anodic to steel. Hence, from the above examination it was deduced that the behavior of zinc coatings would be sufficient at 400°C.