Considerations for the Evaluation of Fouling Resistant Coatings for Centrifugal Compressors

For over forty years, coatings have been used as a means to prevent the build-up of foulants on the flow passages of centrifugal compressors. In general, this has been a “One Size Fits All” solution, with most OEMs and applicators offering nearly identical coating systems, despite the fact that there are distinct differences in the types of foulant that occurs in different services. To develop new coatings, there are two options, test “on the job” or test in a laboratory setting. This paper looks at various test methods to evaluate coatings by isolating the important aspects that a good fouling resistant coating should possess, namely fouling, erosion, and corrosion resistance. Each of these will be investigated separately in a battery of easy to perform tests. To the extent possible, the tests for each aspect attempt to replicate the complex conditions that occur in a centrifugal compressor that impact that specific aspect. The fouling and corrosion tests were performed with considerations for two different types of service. To illustrate the ability of the test to evaluate various coatings, the results from three different coatings will be discussed. These test methods will also be compared to other test methods used in literature.

Non-destructive Testing of Metal-Polymer Laminates with a Digital Holographic Vibrometer

This paper presents the use of a digital holographic vibrometer to investigate metal-polymer laminates by non-destructive testing. A polymer strip was glued to a metal one of the same size. Connection defects could be detected by a local change of the vibration amplitude, even when hidden from view for the observer. The amplitudes of the oscillations excited in the samples were up to 40 nm. This method proved to be non-destructive, allowing the samples to be (re)used after testing, or being studied with other test methods.

Preparation and study of Fe–Co–Zr–B nano-soft magnetic alloy

The mechanical alloying of Fe–Co–Zr–B mixed powder has been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and other test methods. The results show that the Fe–Co–Zr–B nanocrystalline alloy can be produced by mechanical alloying from the elements powders by ball milling of 50 h. With the increase in Co content, the grain size increases correspondingly, and the size of composite particles decreases continuously. The mechanical alloying process of Fe–Co–Zr–B alloy system is slowed down by the addition of Co.

Trace Al-Ti-C-Ce on Solidification Structure Transformation and Fracture Properties of Al-Cu-Mn Alloy

As a kind of refining agent, Al-Ti-C-Ce intermediate alloy is widely used in the field of nonferrous alloy smelting. The effect of Al-Ti-C-Ce contents on microstructure and properties of Al-Cu-Mn alloy was studied by OM, SEM, EDS and other test methods. The results show that the as-cast microstructure of Al-Cu-Mn alloy is obviously refined after adding 0.1% Al-Ti-C-Ce, and the θ phase is characterized with the shape of point or strip. With the increase of the addition amounts, parts of the grains coarsened. When the addition amount reached to 0.3%, the refinement effect of the alloy microstructure was further reduced, and the number of intergranular precipitates TiC and Al3Ti increased. Ductile fracture is the main failure mode of the alloy. After T6 heat treatment, the grain size changed little, and the number of θ phase, TiC and Al3Ti decreased, changed from the mesh to the point or needle or strip structure, and the proportion of alloy ductile fracture increased. The addition of Al-Ti-C-Ce has positive effect on improving the microstructure and properties of Al-Cu-Mn alloy.

Adhesive Content Influence on Antimicrobial Properties of Pineapple Leaf Fiber

This study tests the antimicrobial properties of pineapple leaf fiber. Scanning electron microscopy (SEM), infrared analysis (IR) and other test methods were used to examine the microcosmic morphologies of pineapple leaf fiber. As the pineapple leaf fiber adhesive content reduce fiber antibacterial. Adhesive content 54% of fiber to escherichia coli and staphylococcus aureus antibacterial value is maximum. With further reduce fiber adhesive content, fiber antimicrobial declined obviously. The results indicate that the anaerobic bacteria can’t survive in the inside of pineapple leaf fiber where exist a large specific surface-area, lots of holes and Voids, and much oxygen. Pineapple leaf fiber contains a lot of phenols and their derivatives which are effective natural bacteria resistant materials and inhibit the metabolism and physiology of bacillus and other microorganism,break the structure of germ, and repress the generation of bacillus until the death of germ.Moreover, the existence of a small amount of cannabinol is adequate to kill the microorganisms.

Analog Circuits Test by Using Principal Component Analysis

In view of the difficulties caused by determining threshold for analog circuits test, a method based on principal component analysis (PCA) of node voltages was proposed to overcome these difficulties. At first, the principal component model of fault-free circuits was constructed. Then the circuits-under-test was compared with the principal component model to calculate the statistic for fault detection. The proposed method was used to test the output signal amplifying circuit, which is used in the ultrasonic liquid sensor. The testing results show that the PCA based method has a higher sensitivity than other test methods. And the proposed method can overcome the difficulties in determining threshold by the expert’s empirical knowledge. These make it a suitable candidate for analog circuits test.