Coatings & Surface Engineering

The Coatings & Surface Engineering is the place for conversation and discussion about coatings; substrate modifications; cleaning and surface preparation; and friction, lubrication and wear. Here, you'll find everything from application ideas, to news and industry trends, to hot topics and cutting edge innovations.

Defects Actually Strengthen Roman-era Concrete

Posted January 23, 2017 12:00 AM by Engineering360 eNewsletter

Small defects known as screw dislocations help account for the superiority of the Roman Empire's concrete. These defects provide small-scale plasticity that allows hardened concrete to adjust to stress over time. Researchers say that this new knowledge paves the way for designing stronger concrete and other complex materials.

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7 comments; last comment on 01/25/2017
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Bioactive Film Improves How Implants Bond with Bone

Posted August 25, 2016 12:00 AM by Engineering360 eNewsletter

Researchers from several universities have developed a technique for coating polymer implants with a bioactive film that significantly increases bonding between the implant and surrounding bone. The polymer, polyether ether ketone, also known as PEEK, has properties that make it appealing for use in implants, but it doesn't bond well with bone. The research team tested several methods to coat the polymer, including using a thin film of yttria-stabilized zirconia followed by a coating of hydroxyapatite. The team then heated the coating with microwaves, which makes the crystalline hydroxyapatite structure more stable in the body and more capable of bonding with bone.

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1 comments; last comment on 08/29/2016
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What's Your Favorite Wood Finish?

Posted August 11, 2016 7:00 AM by cheme_wordsmithy

This question is for all you CR4ers who love working with wood. The universe of wood finishes is a big one. There are so many different kinds available depending on the protection you need and the look you want on your project. For the novice craftsman, the finishing step can be daunting, especially since it truly can make or break your project.

As I became more invested in woodworking, I began researching more about different finishes. I found it helpful to break down the myriad of coating products into different types, starting with the most basic categories: surface finishes and penetrating finishes. Penetrating finishes are those that absorb into the fiber of the wood, while surface finishes don't penetrate far and instead build up on the top of the wood's surface. Of the penetrating finishes, I found there were three common types used.

The first is linseed oil, which originates from flaxseed and is available in either "raw" or "boiled" forms. The boiled form is often preferred, as drying chemicals are added to accelerate the otherwise week-long curing time. In order to dry properly, the oil must penetrate the wood and any excess must be removed from the surface after application. Linseed oil will add a yellow hue to the wood which will darker over time, and it brings out the grain of the wood nicely with a soft gloss. It is often used as a medium with wood-coloring oils and stains. It is easy to apply, but on its own does not provide protection against water or UV rays. However it can be mixed with varnish to enhance these properties. Linseed oil also has a short shelf life, and shouldn't be used if it gets thick in the can.

Number two is tung oil, a deep penetrating oil that originates from the tung tree. It is the most protective natural oil finish available, providing some water and UV resistance for the wood. Tung oil is often sold in mixtures with varnish, but "100 percent pure" tung oil is a favorite for those seeking a natural finish which enhances the organic look of the wood. It is slightly less yellowing than linseed oil, doesn't darken over time, and dries to a matte (non-glossy) sheen. Being all-natural, pure tung oil is safe (FDA approved) for contact with food, making it a popular finish for wooden utensils. It also has a long shelf life: pure tung oil can last many years if properly stored. The downside to tung oil is its long drying time (at least 2 days) and curing time (at least 2 weeks), as well as the need for multiple coats (at least 3 or 4).

The last is Danish oil, a blend of varnish, curing oil (typically tung or linseed), and mineral spirits. Danish oil combines the qualities of penetrating oils with the protective properties of varnish to create a more durable finish than natural oils alone. Drying and curing times for Danish oil are slightly shorter than all-natural oils alone. However, Danish oil still requires multiple coats.

A safety note for those new to wood finishing: finishes like Danish oil and boiled linseed oil which contain drying chemicals are susceptible to spontaneous combustion if left in a pile or hot container. Please ensure to hang your rags or towels out individually when drying, or soak them in water to prevent any chance of starting a fire.

Of the penetrating oils I discussed, I will admit I've only personally used Danish oil, but I was happy with the results I got. Aside is a picture of a decorative wood spoon I finished with Danish oil, followed up with a coating of paste wax to add some shine. For all you fellow woodworkers who've used these types of oils, I encourage you to share your projects and let us know your favorites!

20 comments; last comment on 09/10/2016
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Heads Up: Computer Display on Contact Lenses

Posted March 16, 2016 12:00 AM by Engineering360 eNewsletter

Researchers from the University of South Australia have developed a film coating that may turn your ordinary contact lenses into computer screens. The film, a biocompatible, conducting nanoscale polymer, conducts electricity directly onto the lens, opening the possibility for miniature electric circuits that can be worn safely, as well as unobtrusively. The film shows promise for a wide range of applications, from sensors that measure glucose levels in the blood to electronic displays that can be worn directly in the eye.

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4 comments; last comment on 03/21/2016
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A Sharp Solution to Water Treatment

Posted February 18, 2016 12:00 AM by Engineering360 eNewsletter

In many parts of the world, clean water is luxury. An Engineers Without Borders chapter at Utah State University teamed up with a rural town in Mexico to solve a water purification problem in an innovative and sustainable way. Using concrete, washed sand, and PVC pipes, they created a filtration system with one rather surprising component - rusty nails. The town's water was contaminated with arsenic, but the nails removed the toxin by forming a precipitate in which the arsenic sits on the surface of the iron. Water passes over the nails, through a diffuser plate, and then through a sand and gravel filter, removing both arsenic and bacterial pathogens.

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9 comments; last comment on 02/19/2016
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