| 摘要 |
<p>Moulds and cores for metal casting are made from moulding sand consisting of quartz, binder such as clay or bentonite, and water, and in addition, small amount, pref. 0.002-0.5 (0.01-0.08)wt.% (calcd. on total wt.), material predominantly consisting of aromatic and/or alicyclic hydrocarbons with up to 6, advantageously 2-5, nuclei. Pref. additives are alicyclic and/or aromatic hydrocarbons with 2-6 nuclei in which nuclei are condensed to one another, or bonded by bridges with one or more active double or triple bonds or condensed and bonded by bridges or pref. mononuclear additives are 1-ring cpds., such as cycloparaffins, present as derivs. of small, normal or large rings, in such a way that under pyrolytic conditions, lustrous C separates from 2- to 6-nuclear cpds., with ring cleavage.</p> |
