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Epoxy resin aluminum oxide

In order to provide the required flame retardancy to the molding compound, an encapsulated formulation usually contains brominated resins and antimony oxide. The brominated resins used in the encapsulated formulation are mainly tetrabromobisphenol A (TBBA) based epoxy resin or brominated epoxy novolac. These bromine-containing additives were reported to cause bond degradation at high temperature through accelerated void formation in the gold-aluminum intermetallic phases (1-4). [Pg.391]

For example, a crushed coal sample will be formed into a briquette with a cold-setting epoxy resin. When the resin is set, the surface is ground using water-resistant, adhesive-backed silicon carbide papers of grit size numbers 240, 320, 400, and 600. Then, polishing is carried out using aluminum oxide powders of specified sizes followed by treatment with a nap-free cloth of cotton and silk and chemo-textile material backed with water-resistant adhesive. There are, of course, suggested sequences for this procedure to produce a surface suitable for microscopic examination. [Pg.112]

A typical thermally conductive epoxy system used as an adhesive, as well as for other purposes, has a thermal conductivity of 0.0026 cal/cm/sec/°C and a volume resistivity of 1.5 x 10 ohm.cm (1.5 x 10 ohm.m). Fillers include alumina (aluminum oxide), beryllia (beryllium oxide), other unspecified inorganic oxides, boron nitride, and silica. Boron nitride is an excellent choice as a thermally conductive filler except that its content reaches a maximum at about 40% by weight in epoxy resins. The resultant products are always thixotropic pastes. BerylUa powder has excellent thermal conductivity by itself, but when mixed with a resin binder its conductivity drops drastically. It is also highly toxic and high in cost. Alumina is a commonly used filler to impart thermal conductivity in resins. ... [Pg.75]

A study by Comyn et al. [8] indicated that low (or no) cure took place in the interphase between an amine cured epoxy and aluminum because the amine was preferentially adsorbed onto the aluminum oxide on the aluminum. Garton et al. [9] showed that the acidic surface of a carbon fiber selectively adsorbed amine and catalyzed the reaction between the amine and an epoxy resin. Nigro and Ishida [10] found that homopolymerization of epoxy resin was catalyzed by a steel surface. Zukas et al. [11] discovered, in a model system of an amine cured epoxy resin and an activated aluminum oxide, a change in the relative rates of the reactions leading to crosslinking of the epoxy, so that the material in the interphase was structurally different from that in the bulk. [Pg.6]

Zinc borate can be used as a fire retardant in PVC, polyolefins, elastomers, polyamides, and epoxy resins. In hal( en-containing systems, it is used in conjunction with antimony oxide, while in halogen-free systems it is normally used in conjunction with other FRs such as aluminum trihydrate, magnesium hydroxide, or red phosphorus. In a small number of specific applications, zinc borate can be used alone. [Pg.329]

Encapsulation is often performed with resins containing fillers such as mica, aluminum oxide, milled glass fibers, and many others. Although epoxies are the resins most generally used, polyesters, filled and unfilled silicones, urethanes, and polysulfides are also used. By the proper choice of fillers it is possible to match expansion rates of the electronic part and the encapsulant, increase the thermal conductivity of the part, and considerably upgrade the electrical and mecharucal properties of the assembly. [Pg.159]

Corrosion resistance can be improved in epoxy adhesives by the addition of suitable fillers. DGEBA-resin-based adhesives show improved resistance to anodic debonding when used to bond steel/polyolefin laminates by the incorporation of aluminum oxide.Levels of aluminum oxide can be varied from 3-40 weight % of the total adhesive composition. [Pg.169]

Another way in which the adherends can potentially modify the properties of an adhesive is by affecting the cure reaction. Some interesting observations in this respect have been reported by Comyn et a/. These workers were examining the suitability of inelastic electron tunneling spectroscopy (lETS) for the study of the interface between an epoxy adhesive and aluminum oxide. The lET spectra of a DGEBA resin and an amine... [Pg.365]

Figure 104. Flame-sprayed aluminum oxide coating on steel, DIC. The sample was mounted in epoxy resin before sectioning. Arrows indicate cavities, which have a gray tone that differs only slightly from the aluminum oxide. Figure 104. Flame-sprayed aluminum oxide coating on steel, DIC. The sample was mounted in epoxy resin before sectioning. Arrows indicate cavities, which have a gray tone that differs only slightly from the aluminum oxide.
Figure 106. Flame-sprayed aluminum oxide coating on steel, with contrast enhanced by Pt/02, BF. The sample was impregnated with epoxy resin before sectioning and then mounted in epoxy resin. The gap at the boundary between the ceramic and the metal (see arrows) is filled with resin, which indicates that this defect was already present before sectioning. The impregnated cavities are dark, the aluminum oxide is gray, and the steel substrate is bright. Figure 106. Flame-sprayed aluminum oxide coating on steel, with contrast enhanced by Pt/02, BF. The sample was impregnated with epoxy resin before sectioning and then mounted in epoxy resin. The gap at the boundary between the ceramic and the metal (see arrows) is filled with resin, which indicates that this defect was already present before sectioning. The impregnated cavities are dark, the aluminum oxide is gray, and the steel substrate is bright.
In epoxy resin, the combination of ATH and phosphonium-modified clay additives showed superposition or even synergetic behavior for nearly all fire retardancy properties. Schartel et al. suggested that the presence of ATH resulted in an increase in residues and a small decrease in effective heat of combustion because of dilution of the pyrolysis products [24], Both fire retardancy mechanisms have their primary source in the conversion of ATH into aluminum oxide, which increased the residues, and water, which diluted and cooled the flame zone. In addition, the presence of organophosphorus decreased the effective heat of combustion through a gas phase. Most of the phosphorus was liberated during polymer pyrolysis and influenced the Are behavior through flame inhibition. [Pg.318]

Easily dehydrohaiogenated or dehydrated compounds, such as hydrated oxides, reduce the formation of flammable products by the endothermic effect that accompanies their transformation. Examples are AI2O3 - 3H2O used for epoxy resins [37] and mainly hydrated aluminum hydroxides [12]. They are cheap in cost but their low efficiency, compared to halides, necessitates that a large quantity (50-80% by weight) be used, and this affects the properties of plastic materials. In spite of this, aluminum hydroxides represent about 50% of all flame retardants used in the United States, the rest being made of Sb203, bromine and chlorine compounds, phosphates, and phosphorus-halide compounds [38]. [Pg.212]

Table 2 lists thermal conductivity values for several metals as well as for beryllium oxide, aluminum oxide, and several filled and unfilled resins. Fig. 2 shows the thermal conductivity for an epoxy resin as a function of volume fraction of heat-conductive filler. [Pg.708]

The best current 100% solids epoxy adhesives contain about 70% aluminum oxide by weight and give thermal conductivities in the range of 0.8-1 in the English units shown in Table 2. For convenience, a conversion chart is included in Table 2 to permit conversion to any other set of units. The k values for the best alumina-filled epoxies are 10-12 times greater than for unfilled epoxy resins, but are still much lower than for pure metals or solders. Nevertheless, heat flow is adequate for bonding most components. For example, an adhesive with a thermal conductivity of 0.91 and a bond thickness of 3 mils would be able to transfer about 20 W/cm of surface area, with a AT only about 10 C above the heat sink temperatures ... [Pg.709]

In the following sections, some work is presented in which the properties of nano- and microparticle filled composites were determined under variation of the filler contents. These materials were made on the basis of standard epoxy resins cured by amine hardeners. The nanofillers were aluminum oxide (AljOj, 13 nm), titanium dioxide (Ti02, 300 nm and 20 nm) and also calcium silicate (CaS103,5-10 /xm) microparticles. All these fillers are commercially available as powders. The composites were prepared by mechanical mixing using a Dissolver mixing device, as shown in Figure 3. [Pg.50]


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