ANALYSIS OF THERMAL DECOMPOSITION PROCESSES OF MOLDING MIXTURES IN CASTING PRODUCTION AND ITS IMPACT ON CASTING QUALITY
Keywords:
Quyma jarayoni, qolip aralashmasi, termik parchalanish, gaz ajralishi, fenol-formaldegid smola, karbonizatsiya, gazli g‘ovaklik, quyma nuqsonlari, TG/DTGtahlili.Abstract
Ushbu maqolada quyma ishlab chiqarish jarayonida qo‘llaniladigan qolip aralashmalari tarkibidagi kvarts qumi, bentonit, ko‘mir kukuni hamda fenol-formaldegid turidagi organik bog‘lovchilarning yuqori harorat ta’sirida (1400–1700∘C) termik parchalanish jarayonlari tahlil qilingan. Termogravimetrik (TG/DTG) va gaz xromatografiyasi tahlillari asosida termik parchalanish jarayoni besh asosiy bosqichda kechishi aniqlangan. Erkin va adsorbsiyalangan namlikning ajralishi (25–200∘C), gley suvsizlanishi va bog‘lovchining dastlabki parchalanishi (200–400∘C), fenol-formaldegid smolasining intensiv destruksiyasi (400–700∘C), karbonizatsiya (700–1000∘C) hamda yuqori haroratli reaksiyalar (1000–1700∘C). Parchalanish natijasida CO, CO2 , CH4 , H2 hamda uchuvchan organik birikmalar (VOCs) ajralib chiqishi qayd etilgan. Mazkur gazlarning qolip ichida bosimni oshirishi natijasida quyma metall tarkibida gazli g‘ovaklik, mikrobo‘shliqlar va sirt nuqsonlari hosil bo‘lish mexanizmlari baholangan. Tadqiqot natijalari qolip aralashmalari tarkibini optimallashtirish va past gaz ajratuvchi bog‘lovchilarni qo‘llash orqali quyma sifatini oshirish imkoniyatini ko‘rsatadi.
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