Two-component Coatings Research Articles

Automated determination of pot life of two-component reactive coatings

The process of pot life screening of two-component coatings is significantly accelerated by using an automated coating formulation system with viscosity measurement capability. High-throughput methods are revolutionizing the processes used in polymer and coatings development. A high-throughput approach to characterize the effect of formulation variables on pot life of two-component solventborne coatings is presented. Using an automated formulation system with viscosity measurement capability, the viscosity of the coatings formulations is measured periodically to determine the viscosity–time profile. As examples, variables such as catalyst type, catalyst level, polyol composition, polyol to isocyanate ratio, and pot life extender were selected as formulation variables and their role in pot life were explored. Compared to traditional pot life determination methods using efflux viscosity cups, the high-throughput approach greatly improves the speed and efficiency of the process and allows many more compositions to be explored.

Electrical properties of contacts covered with multicomponent coatings by the dynamic ion mixing

The paper presents the results of operational characteristics measurements on electrical contacts covered with two-component coatings of Ni+Au, Au+W, Pt+Au and Ni+Ag on copper surfaces. A method of one-beam dynamic ion mixing has been used to deposit those layers. An essential depth redistributing the deposited atoms is revealed by AES spectroscopy. Energy of an electrical arc that formed when the contacts get opened has been determined. It has been found that the coatings reduce mean energy of the arc between contacts from 1.74 J for pure copper down to 1.12 J for a coating of Au+W.

Scratch resistance behavior of automotive plastic coatings

The sensitivity of automotive coatings, particularly coatings for plastics, to scratching has been a growing concern among automakers. Scratching may result from such predelivery events as polishing of minor defects embedded in the paint, or post-delivery events such as car wash bristles, dirt embedded under a cloth utilized in polishing the car, tree branches, and the like. Warranty cannot separate out which event is the more prevalent (e.g., predelivery or post-delivery to the customer) form of damage on plastics. Data available on coatings for metal, however, does suggest that isocyanate-based crosslinked systems perform more poorly than their melamine-based crosslinked counterparts when exposed to in-plant (predelivery) handling. This work attempts to correlate the scratch resistance behavior of coatings of plastics, both in their “green state” (right out of the oven, less than one week post-cure time) and in their infancy in the field (simulated 250 kJ Xenon arc Weather-ometer), to surface attributes such as toughness, hardness, and elasticity. Functional carbamate-melamine crosslinked one-component coatings and functionalized silane-melamine crosslinked one-component coatings appear to out-perform selected two-component coatings, which in turn outperform one-component hydroxyl functional acrylic or polyester melamine crosslinked coatings. Material attributes such as surface hardness, toughness (as measured through the method of essential work), and the ability to recover from an applied load are most important in the ability of the coating to resist damage.

Characterization of Two-Component Metal Coatings (Al/Sn) with SIMS

Vacuum deposited films of immiscible metal–metal systems can be applied as tribological coatings for plain bearings in high performance diesel engines. These industrially manufactured coatings show higher lifetimes than conventional electroplated coatings. For our investigations we used aluminum-tin coatings of 1 μm thickness on a glass substrate produced by sequential deposition from two separate targets under working gas pressure of 0.4 Pa. The tough Al matrix takes high mechanical loads and the soft inclusions of Sn act as solid lubricant. While Sn is deposited it migrates on the Al surface and grows as islands. We characterized the conformation and the distribution of the Sn islands on the surface and to the interstitial area between the islands with 3-D secondary ion mass spectroscopy (SIMS). The existence of a Sn layer between the islands (“wetting layer”) has been detected by SIMS and verified by measurements with Auger electron spectroscopy (AES).

Options for painting hydraulic tubes

Powder coatings offer the most economical solution for coating hydraulic tubes, but several practical issues need to be resolved before going ahead with this strategy. If powders cannot be used then dip application of liquid coatings offers the next most efficient method, but even this option has potential difficulties associated with it, especially if two-component coatings are to be used. If spray application remains the last practical method, then electrostatic spray guns should be preferred to nonelectrostatic applications such as conventional air atomizing or HVLP. In most cases it is unlikely, but not impossible, that any of the spray methods will achieve TEs in the 80 to 90% range as can be achieved by either powder or dip coatings.

The Texture and Macrostress Measurements for Cutting Tool PVD Coatings

The details of X-ray techniques such as fluorescence thickness measurements, residual macrostress and texture determination for mono- and multilayers coatings of HSS and CC cutting tools are considered. The features of macrostresses measurement concern with thin high textured coatings are considered. The macrostress phenomenon concern with difference of thermal extension coefficient (TEC) of coating and substrate, deposition parameters and layer sequence in the multilayer coatings are discussed. The macrostress data concern with cutting performance of coated milling inserts are considered. High compressive residual stresses and pronounced {111} texture for HSS and weak compressive or tensile stresses for CC it is revealed for monolayer TiN coatings. The multilayer coatings TiN/Ti/TiN... are designed to minimize the stress level. The specific texture of alternating layers like Ti, TiB 2 , Al 2 O 3 , AIN and SiC, which have the TEC anisotropy (α c ¬= α a ), can be used for governing of macrostress. Ultra-high macrostresses up to 16000 MPa have been revealed for Zr-N, Zr-N-C, Zr-Nb-N and Zr-Nb-N-C coatings on HSS. The texture of ZrN phase for the polycomponent coating systems have more strong technology sensitivity in comparison with two-component coatings.

A Technologically Acceptable Coating Synthesis Based on the Flip-flop Synthesis Method

Abstract The flip-flop synthesis method was suggested by Southwell for synthesis of two-component multilayer coatings. The introduction of a third refractive index is proposed in order to simplify the resulting systems and make them technologically feasible. The thickness optimization procedure, which avoids very thin layers, is recommended. Two examples of synthesis of broad-band anti-reflection coatings are presented.

Ratio Sensitivity in Two-Component Coatings

This paper reports the development of the statistics for pre dicting the ratio sensitivity of polymer chain length in cross-linked two- component polymer systems. Experimental evidence is presented to sup port the theoretical conclusion that the chain length obtained when poly merizing two tri-functional monomers is very insensitive to the ratio of component A to component B. These results have considerable practical implications for the possible growth of two-component coatings' use.