Relation Between Roughness of Interface and Adherence of Porcelain Enamel to Steel

Abstract

SUMMARYPorcelain-enamel ground coats were prepared and applied under conditions that gave various degrees of adherence between enmel and a low-carbon steel (enameling iron). The variations in adherence were producedby (a) varying the amount of cobalt-oxide addition in the frit, (b) varying the type of metallic-oxide addition in the frit, keeping the amount constant at 0.8 weight percent, (c) varying the surface treatment of the metal before application of the enamel, by pickling, sandblasting, and polishing, and (d) varying the time of firing of the enamel containing 0.8 percent of cobalt oxide.Specimens of each enamel were given the standard adherence test of the Porcelain Enamel Institute.' MetaUographic sections were made, on * which the roughness of interface was evaluated by counting the number of anchor points (undercuts) per centimeter of specimen length and also by measuring the length of the interface aud expressing results as the . ratio of this length to the length of a straight line parallel to the over-all direction of the interface.The following conclusions were drawn from the data:(1) A positive correlation was found between the adherence of a porcelain-enamel ground coat end the roughness of the interface.(2) In general, adherence correlated better with anchor points per centimeter than with the increase in interracial uea (interface ratio).(3) The method of metal preparation had a marked effect on the relation between roughness of interface and adherence of porcelainensmel ground coats to enameling iron. In general, better adherence was associated with enamels applied to pickled iron than to sandblasted iron for the sane degree of roughness of interface.. (4) Most of the ro~hness that was associated with good adherence between a porcelain-enamel ground coat and iron developed during the . firing process.(5) Roughness of interface is a necessary, but not a condition for the development of good adherence between a enamel ground coat and iron.NACA TN 2934 sufficient, porcelain-(6) One or more factors other than roughness of interface also influence the adherence between a porcelain-ensmel ground coat and iron.

Oxidation Resistance and Microstructure Evaluation of a Polymer Derived Ceramic (PDC) Composite Coating Applied onto Sintered Steel

“…Although pyrolysis at 700 °C was not enough to seal the coating and create a barrier, as previously indicated (Figure 4), this temperature already promoted the infiltration of the substrate surface. Enamel coatings are known to adhere to steels due to mechanical anchoring into the surface roughness [46,47,48], an effect which can be further increased in sintered steels due to their intrinsic porosity. Furthermore, the absence of cracks between the coating and the steel substrate indicates good adhesion, while the presence of cohesive cracks in the coating, indicated by the white arrows in Figure 5a, supports that this class of PDC barrier coating fails by cohesive rather than by adhesive mechanisms [25].…”

Micro‐alloys precipitation in NiO‐ and CoO‐bearing enamel coatings and their effect on adherence of enamel/steel

“…Among all the metal oxides, CoO and NiO are the two best choices. Therefore, many studies have been conducted to investigate their roles in enhancing enamel‐steel interfacial adherence, and micro‐alloy precipitations at the interface between steel and enamels . These different micro‐alloy precipitations affect their adherence .…”

“…Therefore, many studies have been conducted to investigate their roles in enhancing enamel-steel interfacial adherence, and micro-alloy precipitations at the interface between steel and enamels. [16][17][18][19][20][21][22][23][24][25][26][27][28] These different micro-alloy precipitations affect their adherence. 17,19,21 However, little attention has been paid to understand the formation of these microalloy precipitations and their contribution to the enamel/ steel adherence.…”

Effect of Crystallization Temperature on the Microstructures and Mechanical Properties of Enamel Substrate RT330

“…In addition, the enameled heat sink is also operated continuously under elevated‐temperature environment (200–300 °C) in the nuclear power station. Therefore, research on the effect of crystallization temperature on the microstructures and mechanical properties of enamel substrate is an important piece of engineering research for the processing technology of enameled substrate …”