Harrick Scientific Products, Inc.

	Tribology-the study of friction, wear, and lubrication-is important in mechanical, electromechanical, and biological systems. Changes in materials due to abrasion, friction, lubrication, erosion, and corrosion result in failures of the moving components during use. These effects are usually minimized by careful surface finish design and lubrication. Recycling and refinishing surfaces can extend the lifetimes of components. By examining worn surfaces, better methods can be developed to prevent wear. This applications note uses infrared spectroscopy to study tribology changes in steel.

	The sample investigated was 28 mm in diameter by 8 mm thick with a carbon-based coating. The sample was lubricated, tested, and then cleaned with n-heptane, leaving chemisorbed species in the wear scratches on the surface.

	The spectra of the disc were measured on an FT-IR spectrometer equipped with the Harrick VideoMVP™ (see Figure 1). The background spectrum was collected from the clean ATR crystal. Then the sample was placed, face down, on the diamond crystal and positioned over the area of interest using the image on the display. The pressure applicator was lowered to apply ~240 N of force to compress the sample against the crystal. The spectrum and image were then recorded. All spectra were collected from 4000 to 400 cm

	Figure 2 shows spectra measured from a section with wear scratches in comparison to a shiny smooth section, along with photographs of the areas of each sample that were examined. The infrared spectrum of the wear scratches show a weak broad band in the –OH stretching region and additional bands at 1450 cm

, all of which are not present in the unworn section. This indicates that a residue from the lubricant or chemisorbed species remains in the worn area. More detailed analysis could be used to identify the chemisorbed species.


	Figure 2: ATR spectra and photographs of an unworn area (red) and a worn area (blue) of a flat metal part.

	The results presented here clearly show that diamond ATR can be used to examine tribology materials. The viewing capabilities and small sampling area of the VideoMVP allow for inspection of the wear scratches in comparison to the unworn areas.


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A Diamond ATR Study of Worn Surfaces on Metal

Multiple reflection attenuated total reflection FT-IR accessory allows for protein analysis of strongly IR-absorbing samples, such as aqueous solutions.

Analysis of Protein Standard Solutions by ATR-IR

	Coatings on glass are used in a variety of industries, including automotive, packaging, architectural and decorative. These coatings serve to protect from UV damage and from weathering under hot and humid conditions; increase material strength; facilitate cleaning; and save energy. These coatings are generally very thin and can be a challenge to be measured by infrared spectroscopy. This application note demonstrates the utility of using a high-throughput single-reflection diamond ATR to study these thin coatings on glass.

	Infrared spectra were collected on an FT-IR spectrometer equipped with the Harrick DiaMaxATR™ single-reflection high-throughput diamond ATR accessory. The system was purged to remove water vapor and CO

resolution and signal averaged over 32 scans. A background spectrum was collected. The glass samples were placed with the coated side against the crystal with optimum force applied to achieve close contact with the diamond ATR element. Five samples were measured all soda lime silica glasses: one untreated, one showing corrosion and three with ~225 nm thick SiO

 coatings having differing oxygen and nitrogen content.

	Figure 2 shows the resulting spectra. The spectrum of the corroded glass shows the formation of hydroxyl groups, with the broad band at 3400 cm

. This band has at least two shoulders, indicating that there are –OH bands bound to the surface somewhat differently. The band at 1402 cm

 is likely due to an –OH bend. The structure in the 920-761 cm

 region also shows changes due to corrosion, which is probably some combination of shifts in the Si-O-Si stretch due to the presence of the hydroxyl groups and possibly due to the formation of –SiH. The coated glass also shows hydroxyl groups in around 3400 cm

. Additional structure in this region is more pronounced for the samples having higher Si and N content as is the intensity of the band near 761 cm

	The Harrick DiaMaxATR, high throughput, single reflection ATR is an effective tool for examining thin films on glass. In this particular case, closer examination of the spectra in the fingerprint region of the coated samples would further elucidate the structures formed by the coatings having slightly different chemical composition.


	141 Tompkins Ave., Box 277, Pleasantville, NY 10570
	tel. (914) 747-7202, fax (914) 747-7409
	Website: 

A Diamond ATR Study of Thin 225 nm Films on Glass

This applications note explores the potential of using a highthroughput single-reflection diamond ATR to detect structural changes in egg yolk upon heating.

Author | Harrick Scientific Products, Inc.

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