Liivapritsis kasutatud kõlbmatu abrasiivi korduvkasutuse rakendused

Töö eesmärk oli uurida liivapritsis kasutatud kõlbmatut abrasiivi ning leida sellele sobivaid korduvkasutuse viise. Töö käigus fraktsioneeriti liivapritsis kasutatud kõlbmatu abrasiiv, kuumutati ja pihustati abrasiivi, testiti korrosioonikindlust. Abrasiivist valmistati erinevaid metalloplaste, arvutati nende tihedused ning arvutati mehaanilised omadused ja määrati elektrieritakistus. Abrasiivist valmistati ka magnetiline spetsiaalvärv. Tööd alustati abrasiivi fraktsioneerimisega, milleks kasutati sõelkomplekti. Fraktsioneerimise eesmärk oli teada saada millised erinevad fraktsioonid abrasiivis on ja millised on nende osakaalud. Kõige rohkem oli abrasiivis 0,1 mm fraktsiooni, mis moodustas pulbri kogumassist 45%. Pulbri sõelumisel tulid abrasiivist välja ka kiulised osakesed. Kõiki fraktsioone ning kiuliseid osakesi vaadati ka mikroskoobiga, mis andis teada milliseid osakesi abrasiiv sisaldab. Järgmisena alustati katsetega abrasiivi sulatada ning kasutada pindamismaterjalina. Abrasiivi kuumutati esmalt hapnik-atsetüleenpõletiga ja seejärel kõrgsageduskuumutiga. Mõlemad katsed ebaõnnestusid kuna oksüdeerunud abrasiivi osakesed ei sulanud omavahel kokku. Abrasiivi prooviti ka pihustada pindamismaterjalina, aga ka see katse ebaõnnestus kuna osa abrasiivist põles ära ning teine osa koosnes oksüdeerunud osakestest, mis ei sulanud piisavalt, et kasutada pindamismaterjalina. Kuna katsed abrasiivi sulatada ja pihustada ebaõnnestusid, siis otsustati valmistada abrasiivist ja polümeervaikudest metalloplaste. Esmalt valmistati metalloplast abrasiivist ja epoksüvaigust. Metalloplaste valmistati erinevate komponentide vahekordadega, et võrrelda nende tihedust ja mehaanilisi omadusi. Lisaks epoksüvaigule, valmistati metalloplaste ka fenoolvaiguga. Fenoolvaigu ja abrasiivi metalloplasti valmistamiseks kasutati kuumpressi. Abrasiivist prooviti valmistada ka tsemendiga segatud komposiiti, eesmärgiga valmistada teistsuguse sideainega komposiit. See katse ebaõnnestus, kuna tsement ei sidunud oksüdeerunud abrasiiviosakesi ning detail oli habras ja lagunes. Metalloplastidel arvutati tihedus ja survetugevus, testiti löögisitkust ning määrati elektrieritakistus. Kõige suurema tihedusega metalloplast oli abrasiiv-fenoolvaigu detail vahekordadega 90:10. Kõige väiksema tihedusega 50:50 abrasiivi-epoksüvaigu vahekordadega metalloplast. Parim survetugevus oli abrasiiv-fenoolvaigu metalloplastil, vahekordadega 60:40, mis on ka arusaadav, kuna detail valmistati kuumpressis 200 bar rõhuga. Testitud detailidest parim löögisitkus oli 50:50 abrasiiv epoksüvaigu komposiidil. 37 Elektrieritakistus oli kõikidel testitud detailidel liiga suur, et lihtsa multimeetriga mõõta. Üks põhjus suurest takistusest on kindlasti see, et vaiguosakesed ümbritsevad abrasiiviosakesi ning takistavad elektrijuhtivust. Korrosioonikindlust testiti kõikidel metalloplastidest detailidel. Katsete põhjal saab öelda, et korrosioonikindlus testitud metalloplastidel on ainult siis, kui epoksüvaiku on detailis vähemalt 40%. Kõikidel fenoolvaiguga tehtud detailidel oli näha roostet. Abrasiivi kasutati ka magnetilise spetsiaalvärvi valmistamisel. Spetsiaalvärviga värvitud pindadele on võimalik kinnitada magneteid. Katsed spetsiaalvärviga värvides õnnestusid ning magnetid kinnitusid värvitud pindadele. Sõelutud ja sõelumata abrasiiviga valmistatud värvidel ei olnud erinevust. Kasutatud abrasiivi rakendamise võimalusi on mitmeid. Abrasiivist on võimalik teha metalloplast, millest omakorda saab teha lisaraskuseid alternatiivina betoonraskustele. Abrasiivi metalloplastina kasutades on võimalik teha ka lillepotte, mille peamine eelis betoonist alternatiivide eest on väiksem tihedus ja seeläbi kergem toode. Metalloplastide peamine miinus on suur hind võrreldes alternatiivsetest materjalidest valmistatud toodetega. Metalloplasti oleks otstarbekas kasutada ainult juhul, kui tootel on vaja kindlaid omadusi ning tal on mitmed eelised võrreldes alternatiividega. Abrasiivist oli võimalik kuumpressida detaile, mistõttu saab teda utiliseerida ka vanametallina, viies vanametalli kokkuostu. Kuumpressimise miinus on detailide suhteliselt suur hind, kuna tootmiseks on vaja kuumpressi ning tootmisel on suur energiakulu. Analüüsi tulemusena selgus, et parim rakendus abrasiivile on spetsiaalvärvi tootmine. Kasutada on võimalik sõelumata abrasiivi, mistõttu on tootmisprotsesside hulk väike. Tootmishinna poolest on spetsiaalvärvi valik kõige madalam. Võrreldes teiste väljapakutud rakendustega täidab abrasiiv spetsiaalvärvina oma ülesandeid kõige paremini.

The goal of this graduation thesis was to study the unsuitable abrasive used in sandblasting process and to find suitable ways to reuse it. During the work, the unsuitable abrasive used in the sandblasting was fractionated, heated and sprayed, the corrosion resistance was tested. Various composites were prepared from the abrasive, their densities and mechanical properties were calculated and the electrical resistance was determined. A special magnetic paint was also made from the abrasive. Work began on abrasive fractionation using a sieve set. The purpose of fractionation was to find out what different fractions are in the abrasive and what their proportions are. The abrasive had the highest fraction of 0.1 mm, which accounted for 45% of the total weight of the powder. When the powder was sieved, fibrous particles also came out of the abrasive. All fractions and fibrous particles were also examined under a microscope to indicate which particles the abrasive contained. Next, attempts were made to melt the abrasive and use it as a coating material. The abrasive was first heated with an oxygen-acetylene burner and then with a high frequency heater. Both experiments failed because the oxidized abrasive particles did not fuse together. Attempts were also made to spray the abrasive as a coating material, but this attempt also failed because part of the abrasive burned out and the other part consisted of oxidized particles that did not melt enough to be used as a coating material. As attempts to melt and spray the abrasive failed, it was decided to make composites of abrasive and polymer resins. First, the composites were made of abrasive and epoxy resin. Composites were made with ratios of different components to compare their density and mechanical properties. In addition to epoxy resin, composites were also prepared with phenolic resin. Hot pressing was used to make the phenolic resin and abrasive composite. Attempts were also made to make a cement and abrasive composite in order to make a composite with a different binder. This experiment failed because the cement did not bind oxidized abrasive particles and the detail made was brittle and decomposed. The density and compressive strength of the composites were calculated, the impact resistance was tested and the electrical resistance was determined. The highest density composite was a ratio 90:10 abrasive-phenolic resin detail. Composite with the lowest density was 50:50 ratio abrasive-epoxy resin. Abrasive-phenolic resin composite with a ratio of 60:40 had the best compressive strength, 39 which is also understandable since the part was made in a hot press at a pressure of 200 bar. The best impact strength of the tested parts was 50:50 abrasive-epoxy resin composite. The electrical resistance of all tested parts was too high to be measured with a simple multimeter. One reason for the high electrical resistance is certainly that the resin particles surround the abrasive particles and impede electrical conductivity. Corrosion resistance was tested on all composite parts. From the tests it can be said that the corrosion resistance of the tested composites is effective only if the detail consists atleast 40% of epoxy resin. All parts made with phenolic resin showed rust. The abrasive was also used to make a special magnetic paint. Magnets can be attached to surfaces painted with magnetic paint. Experiments with special paint were successful and it was possible to attach magnets to the painted surfaces. There was no difference between sieved and unsieved abrasive paints. There are several ways to use the unsuitable abrasive. Abrasive can be used to make composites, which in turn can be used as an alternative to concrete weights. By using the abrasive as a composite, it is also possible to make flower pots, which main advantage over concrete alternatives is a lower density and thus a lighter product. The main disadvantage of abrasive-resin composite is the high price compared to products made of alternative materials. It would only be useful to use such composites if the product needs certain properties and has several advantages over alternatives. It was possible to hot-press parts from the abrasive, so it can also be utilized as scrap metal. The disadvantage of hot pressing is the relatively high cost of the parts, because the production requires a hot press and consumes a lot of energy. The analysis showed that the best application for abrasives is the production of special paints. It is possible to use unsieved abrasive, so the number of production processes is small. In terms of production price, the choice of special paint is the lowest. Compared to other proposed applications, the abrasive performs its functions best as a special paint.