Immersion ultrasonic testing

The HILL-SCAN 30XX boards can be used in different PCs. Desktop- and tower-PCs as well suited for laboratory uses. For in-field inspections rugged notebooks and portable PCs are advantageous. A typical portable system is shown in Fig. 2 (USPC 3010), used in MUSE (Mobile Ultrasonic Equipment). This portable PC not only contains the boards for ultrasonic testing but also a controller with power supply for stepper motors, so that a manipulator can be connected directly. The MUSE system is enlarged with a water circulation system which enables a local immersion technique" for in-field inspections. A typical result is shown in Fig. 3, which presents a D-scan of a CFRP- component in RTM-techniques. The defect area caused by an impact is clearly indicated. The manipulator is described in [3]. 

Bonded structures that are ultrasonically tested by the immersion methods often use a C-scan recorder to record the test. This recorder is an electric device that accepts signals from the pulser-receiver and prints out a plan view of the part. The ultrasonic search unit is automatically scanned over the part. The ultrasonic signals for bond or unbond are detected from built-in reference standards. C-scan NDT techniques are used extensively by aircraft manufacturers to inspect bonded parts. 

Inspection of the conical shell that helps to support the reactor core. The technique, which was developed in concert with the CEA/STA, was performed in late 1999. It involved ultrasonic testing of welds immersed in liquid sodium and located several meters from the scan surface. 

The use of the surface ultrasonic waves seems to be convenient for these purposes. However, this method has not found wide practical application. Peculiarities of excitation, propagation and registration of surface waves created before these time great difficulties for their application in automatic systems of duality testing. It is connected with the fact that the surface waves are weakened by soil on the surface itself In addition, the methods of testing by the surface waves do not yield to automation due to the difficulties of creation of the acoustic contact. In particular, a flow of contact liquid out of the zone of an acoustic line, presence of immersion liquid, availability of chink interval leads to the adsorption and reflection of waves on tlie front meniscus of a contact layer. The liquid for the acoustic contact must be located only in the places of contact, otherwise the influence on the amplitude will be uncontrolled. This phenomenon distorts the results of testing procedure. 

Fig.5. Appearance of installation for the testing of pistons of diesel engines. 1- ultrasonic flow detector 2- electronic blocks 3- electromechanical drives 4- immersion bath 5-controllable detail.

We have observed a dependence of the yield, polymerization degree, and polydispersity of polysilanes on temperature and also on the power of ultrasonication. In the ultrasonication bath the simplest test of the efficiency of cavitation is the stability of the formed dispersion. It must be remembered that the ultrasonic energy received in the reaction flask placed in the bath depends on the position of the flask in the bath (it is not the same in each bath), on the level of liquid in the bath, on temperature, on the amount of solvent, etc. When an immersion probe is used the cavitation depends on the level of the meniscus in the flask as well. The power is usually adjusted close to 50% of the output level but it varies with the reaction volume, flask shape, and other rection conditions. The immersion-type probe is especially convenient at lower temperatures. 

Various membrane materials are to be compared for corrosion resistance in hydrochloric acid. Membrane samples are ultrasonically cleaned with Freon for 5 minutes and dried at 200°C for 2 hours followed by similar steps of ultrasonic cleaning with demineralized water and drying. The conditioned membrane samples are then immersed in 35% HG solution, making sure that no air bubbles are trapped in pores. The acid exposure at the test temperature (e.g. 25°C) continues for a given period (e.g. one week). The tested samples are ultrasonically washed with demineralized water for 5 minutes and dried at 200°C for 2 hours. The weights of the cleaned membrane samples before and after the acid exposure are compared to assess the relative corrosion resistance of various membrane materials. 

The membrane thickness reproducibility was tested over the wafer on 32 evenly distributed membranes. A mean thickness of 61.8 im (s.d. = 7.3 im) was found across the whole wafer, while a lower ( 4 im) typical standard deviation was found on more closely located membranes. Prior to measurements, the membranes are preconditioned in 0.1 M KC1. No degradation of the membrane adhesion was observed during an immersion of 2 hours in an ultrasonic bath containing 0.1 M KC1. 

Consider the configuration of Fig. 7. Ffere the sonochemical vessel is immersed in a tank packed in ice. The transducer is mounted several inches from the open end of the vessel, which is covered by an acoustical window. This window allows the ultrasonic energy to enter the vessel, while preventing the mixing of the tank water (which contains the waste heat of the transducer) with the solution under test. Thus, the transducer waste heat is confined to the tank water, and has no opportunity to enter the treatment... 

XRD patterns were measured with a Rigaku D/max 2500 instrument with Cu Ka. A PHILIPS XL 30 SEM with an EDX detector was employed. The adhesion of the catalyst layer was measured by weight loss in ultrasonic bath test for 30 min, with immersion in petroleum ether in a sealed beaker. 10 cycles of thermal shock was applied by heating to 800 °C for 20 min with a rate 10 C/min, dropping into water at 25 C, and drying at 120 C for each. 

Figure 15.11 Examples of ultrasonic scanning systems, (a) A laboratory immersion tank with test samples and (b) a water squirter.

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