What Are The Glass Quality Requirements For Fiberglass Molding?
Glass fiber forming process, to a very high tensile speed will be the diameter of the millimeter glass flow strand drafting, and cooling curing into micron-sized glass fibers. Obviously, glass quality is an important prerequisite for a continuous and stable fiber forming process.
Glass fiber drawing process on the glass quality requirements include two aspects. First, the requirement of the glass is different from the base glass of the material as little as possible. These substances are mainly three categories, one is the bubble (gas inclusions); another category is the stone (solid inclusions); and then a category of streaks and knots tumor (vitreous inclusions). They are collectively referred to as glass defects. Secondly, it is required in continuous industrial production, the composition of glass fluctuations should be small, that is to say, the composition should be stable.
I. Bubbles
Bubbles is a visible gas inclusions, its size from less than 1mm to several mm. general, <0.8mm called gray bubble, greater than 0.8mm called bubble. The chemical composition of bubbles varies, generally containing O2, N2, CO, CO2, SO2, NO, H0 and so on. Naya Ulevich E aluminum borosilicate glass ball gas analysis, mainly SO and CO2, accounting for about 70% of the total gas content; followed by H0, accounting for about 17%; followed by Nz and O2, accounting for about 12.6%. There are generally five causes of gas bubbles in glass, which can be referred to as primary bubbles, secondary bubbles, air bubbles, refractory bubbles, and iron-induced bubbles.
2. Stones
Stones are one of the most damaging defects. Stones are raw material stones, refractory stones, glass crystalization stones, sulfate inclusions and some other foreign contaminants. All of these stones are much more harmful to wire drawing operations than air bubbles. Most of the breaks in the head are caused by a variety of stones. Even if these stones do not cause breakage, they will greatly reduce the strength of glass fibers.A.Ф.Zak has done a test. The glass was first held in the precipitation temperature zone for 6h, so that the precipitated crystal growth, and then pulled into fibers. It was found that when using sodium calcium glass, the fiber strength is reduced by 19% to 47%, and the aluminum borosilicate fiber is reduced by 27% to 52%. The brittleness of fibers containing crystalline impurities also increased by 9% a 54%.
3.streak
In the composition and physical properties with the base glass is significantly different from the glass body is called streak. If it is in the form of beads and drops, it is also called nodular tumor. Stripes on fiber forming is also very unfavorable. Because of their viscosity than the viscosity of the base glass, so often cause significant changes in fiber diameter, so that the quality of the fiber is reduced; viscosity is too large will also cause breakage.
4. the stability of glass composition
If in continuous production, glass liquid or glass ball composition over time (shift by shift or day by day) change too much, even if the glass in the above three kinds of defects just because such as traps are very little, but still will bring harm to the wire drawing operation this, in the management of a better factory, always pay attention to the glass ball in accordance with the production date of the glass ball in order to use the order of the glass ball. With the cell kiln drawing process, the problem is less acute, but the composition should not be allowed to fluctuate too much. Therefore, variations in glass composition must be controlled, both in the production of glass balls and in the direct production of fibers by the pool kiln drawing method. Production control requires that the test methods for the controlled indexes be simple, fast and also credibly discriminating, meaning that the accuracy and precision of the test methods meet the requirements of the production technology.
