The mechanisms of cavitation erosion of raw and sintered basalt

Abstract

The paper analyzes the morphology of cavitation damage of raw and sintered basalt samples. The experiment was conducted using the ultrasonic vibratory cavitation test method according to the ASTM G-32 standard. During the determination of the resistance to the effect of cavitation, a change in the mass of samples was observed in the function of the cavitation time of operation. The morphology of damage caused by the effect of cavitation was followed by scanning with an electron microscope, and the level of degradation of the surface of the samples was quantified using the image analysis. The results showed a significantly higher degree of resistance of sintered basalt, with a cavitation rate of 0.019 mg/min relative to raw basalt, with a cavitation rate of 0.738 mg/min. After 120 minutes of exposure to the cavitation effect, a smaller number of small pits on the surface of sintered basalt were observed, while a higher level of damage to the surface with the appearance of numerous pits was found in raw basalt, which can be connected in some places to larger and deeper pits in some places. The obtained results indicate the possibility of using sintered basalt for the production of parts that will be exposed to the effects of high cavitation loads.

Comparison of the formation and development of cavitation damage on cast and sintered samples based on basalt

“…The samples of cast basalt (label: CB) were obtained by melting the basalt aggregate at the temperature 1250 °C and casting into sand molds. For the purpose of reducing stress, the casting are thermally treated at 890°C/2h [29].The sintered basalt samples (label: SB) were obtained by pressing the basalt powder of 20 μm grain size at the Leitz press under pressure of 1 MPa and sintering at 1150 °C/2h [30]. The dimensions of samples CB and SB were: (15×15×15) mm.…”

“…During the cavitation erosion test, the mass loss of samples was measured. The formation and development of damage to the surface of the samples was followed by the image analysis using Image Pro Plus software program [27][28][29][30].…”

Coating based on basalt protection metal structures

“…Za ispitivanje kavitacione otpornosti zaštitnih premaza korišćena je ultrazvučna vibraciona metoda (sa stacionarnim uzorkom) prema standardu ASTM G-32 [20,21] i proceduri opisanoj u objavljenim radovima [6,22,23]. Tokom ispitivanja koncentrator mehaničkih vibracija je svojim donjim krajem uronjen u vodeno kupatilo temperature 25±1⁰C.…”

Determination of resistance to cavitation of pyrophyllite samples

“…Kod nemetalnih materijala (keramički materijali, polimeri) tokom ekspozicije javlja se nastajanje i razvoj oštećenja površine sa gubitkom mase bez pojave deformacije materijala. Tokom kavitacije pri urušavanju mehura lokalno nastaju visoke temperature i pritisci (približno 5000⁰C i 1000 bar) u vrlo kratkom vremenskom intervalu (manje od 1μs) [13,14].…”

“…Prema podacima iz literature većina istraživanja u ovoj oblasti odnose se na izučavanje ponašanja metalnih materijala pod dejstvom kavitacije, pre svega čelika i legura aluminijuma [11,13,[15][16][17][18][19][20]. U drugoj polovini dvadesetog veka, razvojem novih materijala, započela su istraživanja njihove primene za sintezu komponenti koje treba izložiti kavitaciji i to: kombinacija metalnih i keramičkih materijala, polimernih, kompozitnih i drugih materijala [14,[21][22][23][24], primena vatrostalnih premaza za zaštitu i povećanje otpornosti na dejstvo kavitacije metalnih konstrukcija [25,26]. Prema podacima iz literature ispitivanja pirofilita u uslovima dejstva kavitacije do sada nisu istraživana.…”