Surface treatment abrasion

Fluorotitanic acid is used as a metal surface cleaning agent, as a catalyst, and as an aluminum finishing solvent (see Metal surface treatments). Fluorotitanates are used in abrasive grinding wheels and for incorporating titanium into aluminum aHoys (see Abrasives Aluminumand aluminum alloys). 

Plasma processing technologies ate used for surface treatments and coatings for plastics, elastomers, glasses, metals, ceramics, etc. Such treatments provide better wear characteristics, thermal stability, color, controlled electrical properties, lubricity, abrasion resistance, barrier properties, adhesion promotion, wettability, blood compatibility, and controlled light transmissivity. 

In the flat/container glass fields a wide range of surface treatments now exist which modify the surface of the glass to confer corrosion or abrasion resistance, improve mechanical strength or optical properties. A number of treatments which claim to improve chemical or corrosion resistance are described in References 31 to 35. 

Before a product coating can be applied to a surface, the surface must be free from contamination. As described elsewhere in this report, many different types of abrasives, alkalines, acids, and solvents, as well as water, are used by industry to clean metal surfaces. Once a part is cleaned, surface treatment such as phosphate coating can be applied if desired. The purpose of surface treatment is to condition or prepare the surface so that the paint forms a better bond with the metal surface. 

Since slower-curing epoxy adhesives systems flow over and wet high-energy surfaces very well, there is little chance for air to become trapped at the interface. As a result, mechanical abrasion is often recommended as a substrate surface treatment prior to application of the epoxy adhesive. The added surface area and the mechanical bonding provided by the additional peaks and valleys on the surface will enhance adhesive strength. If the adhesive does not wet the substrate surface well, such as in the case of epoxy resin on polyethylene, mechanical abrasion is not recommended since it will only encourage the probability of gas voids being trapped at the interface. 

Titanium is widely used in aerospace applications that require high strength-to-weight ratios at elevated temperatures. As a result, a number of different prebonding surface preparation processes have been developed for titanium. These generally follow the same sequence as for steel and other major industrial metal substrates degrease, acid-etch or alkaline-clean, rinse and dry, chemical surface treatment, rinse and dry, and finally prime or bond. Mechanical abrasion is generally not recommended for titanium surfaces. 

Similar surface abrasion processes can be applied on all thermosetting plastics. Mechanical abrasion methods consist of abrasion by fine sandpaper, carborundum or alumina abrasives, metal wools, or steel shot. The following surface treatment procedure is usually recommended for most thermosetting plastics ... 

Cellulosics are normally solvent-cemented unless they are to be joined to another substrate. In these cases, conventional adhesive bonding is employed. Polyurethane, epoxy, and cyanoacrylate adhesives are commonly used to bond cellulosics. Surface treatment generally consists of solvent cleaning and abrasion. Cellulosics can be stress-cracked by uncured cyanoacrylate adhesives and some components of acrylic adhesives. A recommended surface cleaner is isopropyl alcohol. 

Commonly used adhesives for both PET and PBT substrates are isocyanate cured polyesters, epoxies, and urethanes. Surface treatments recommended specifically for PBT include mechanical abrasion and solvent cleaning with toluene. Gas plasma surface treatments and chemical etch have been used where maximum strength is necessary. 

Surface preparations must be carefully controlled for reliable production of adhesive-bonded parts. If a chemical surface treatment is required, the process must be monitored for proper sequence, bath temperature, solution concentration, and contaminants. If sand or grit blasting is employed, the abrasive must be changed regularly. An adequate supply of clean wiping cloths for solvent cleaning is also mandatory. Checks should be made to determine if cleaning cloths or solvent containers have become contaminated. 

Surface treatment can also affect the amount of bloom or surface migration of various active surface agents (lubricants, slip and antislip additives, etc.) and either subsequent migration into a product by surface abrasion or chemical removal, solubility, etc. 

---