Cavitation erosion tests

Lightarowicz, A., Cavilating Jet Apparatus for Cavitation Erosion Testing, Erosion Prevention and Useful Applications, ASTM STP 664, p. 530-549 (1979)... 

Fig. 19.25 Vibratory cavitation-erosion test using magnetostriction...

Practice for making and using U-bend stress corrosion test specimens Recommended practice for laboratory immersion corrosion testing of metals Method for vibratory cavitation erosion test Practice for recording data from atmospheric corrosion tests of metallic-coated steel specimens... 

ASTM G 32, Method for Vibratory Cavitation Erosion Test— This standard presents a test method for determining the susceptibility of an alloy in an electrolyte to cavitation damage using high-frequency vibration. In general, the rate of erosion is determined by weight loss of the specimen. The method contains terminology definitions, a description of the apparatus, test specimen dimensions and preparation, test conditions, test procedures, interpretation of residts, and report considerations. 

There are cavitation erosion tests (21,22) that can be used to assess the resistance of plastics to this form of wear, but there are few laboratories performing these tests and fewer use plastics as test specimens. The original ASTM cavitation erosion test required affixing the test specimen on the end of an ultrasonic horn. This would not work well on plastics. The second generation test used a stationary specimen placed near the tip of a vibrating ultrasonic horn. This test could be used on plastics. The latest test uses a high- pressure water jet to create a cavitation field. 

As noted earlier, cavitation erosion test methods such as the vibratory method (Rg. 6) have also been used to screen materials for service under liquid impingement conditions. 

The phenomenon and mechanisms of cavitation-erosion have been considered in Section 8.8 and here it is only necessary to consider laboratory test methods that have been designed to simulate conditions that prevail in practice and which may be used to evaluate the performance of materials. 

In considering these tests it should be remembered that the phenomenon of cavitation-erosion is often accompained by corrosion effects and that a synergistic effect may operate between the mechanically and chemically induced forms of attack. In fact the term cavitation-erosion-corrosion may often be more applicable in describing the requirements of a test procedure. The subject has recently been discussed by Wood etal. °. 

Assessment of cavitation-erosion is based on mass loss and the results are expressed as curves showing cumulative mass (or volume) loss V5. the time of the test. Eisenberg, have expressed the cumulative mass loss plot... 

Examples of various vibratory test procedures for studying cavitation-erosion of metals in inhibited engine coolants have been given in an ASTM Special Technical Publication... 

D 2809 1989 Test method for cavitation erosion-corrosion characteristics of aluminium pumps with engine coolants... 

Lindheim used the rotating disk test method to measure the cavitation erosion performance of the following E-glass laminates ... 

The GRP generally showed higher cavitation erosion rates than 6 Mo-steel, titanium or high-density polyethylene. Damage incubation times for GRP ranged from a few minutes to almost 2h. No detectable erosion loss was recorded for the other three materials after more than 20 h. However, the author cautions that there are no scaling methods available to relate the high intensity accelerated cavitation test results to in-service performance. 

The formation of cavitation bubbles depends on the rugosity, which often changes during the test. The rate of cavitational erosion therefore does not remain constant. One generally observes an onset period, followed by a transition period during which the rate of cavitation corrosion passes through a maximum before it reaches a steady value (Figure 10.37). The duration of these periods depends on the material. To compare the results obtained for different materials the transition period must be short relative to the time scale of the experiment. 

G 32 Test Method for Cavitation Erosion Using of Vibratory Apparatus... 

ASTM G 32-98, Test Method for Cavitation Erosion Using Vibratory Apparatus [13], describes a standard method for performing cavitation tests. Its scope is listed as follows "This test method produces cavitation damage on the face of a specimen vibrated at high iiequency while immersed in a liquid. The vibration induces the formation and collapse of cavities in the liquid, and the coUapsirrg cavities produce the damage to and erosion (material loss) of the specimen. ... 

ASTM G 32-98 Standard Test Method for Cavitation Erosion Using Vibratoiy Apparatus, Annual Book of ASTM Standards, Vol. 03-02, ASTM International, West Conshohocken, PA. 

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