high pressure valves; cryotechnic; Tribological properties; Ti6Al4V/polychlorotrifluoroethylene; liquid nitrogen
Abstract :
[en] In the development of large, high pressure valves for cryotechnic rocket engines, the Tribology Department of the University of Liege had the opportunity to evaluate the pair Ti6Al4V/polychlorotrifluoroethylene (PCTFE) on a pin-on-disk tribometer in ambient air and liquid nitrogen with the contact pressure and sliding speed ranging, respectively, from 3 to 9 MPa and 0.03 to 0.05 m s-1. Because of the affinity of titanium for halogen elements, such as chlorine and fluorine, which are both present in PCTFE, we noticed the formation of an abrasive compound made of chlorine, fluorine, titanium and aluminium. These elements were detected by electron microscopy. In both environments the heat produced during sliding is responsible for the decomposition of the PCTFE. The surface of the polymer is softened by the heat and embedded abrasive particles then scratch the sliding track of the Ti6Al4V disk. This abrasiveness is confirmed with a three-dimensional stylus profilometer used on the Ti6Al4V disks. The low temperature and neutrality of liquid nitrogen hardly inhibit the decomposition of the polymer. This is related to the poor thermal conductivity of both titanium and PCTFE: the heat produced at the contact is fully available for the chemical reaction between the chlorine, fluorine and titanium, all the more so since this reaction requires little energy to take place. A better understanding of the wear behaviour of the pair PCTFE/Ti6Al4V in both air and liquid nitrogen should lead to the development of a surface treatment which prevents the formation of abrasive particles. We could then use titanium alloys as bulk materials for sliding parts in cryogenic valves and, because of the low specific mass of titanium, could benefit from the subsequent weight reduction.
Disciplines :
Mechanical engineering
Author, co-author :
Bozet, Jean-Luc ; Université de Liège - ULiège > Département de chimie appliquée > Chimie appliquée - Cryotribologie
Language :
English
Title :
TYPE OF WEAR FOR THE PAIR TI6A14V/PCTFE IN AMBIENT AIR AND IN LIQUID-NITROGEN
scite shows how a scientific paper has been cited by providing the context of the citation, a classification describing whether it supports, mentions, or contrasts the cited claim, and a label indicating in which section the citation was made.
Bibliography
Bushan, Gupta (1991) Materials, coatings, and surface treatments. Handbook of Tribology, 1st metric edn., McGraw-Hill, New York; .
Cadman, Gossedge (1979) The chemical interaction of metals with polytetrafluorethylene. J. Mater. Sci. 14:2672-2678.
Toy (1971) Surface-polymerization of tetrafluorethylene on fluorine-activated metal substrates. Journal of Polymer Science Part C: Polymer Symposia 34:273-279.
Noda, Inagaki, Yamada (1969) Glass-like carbons. J. Non-Cryst. Solids 1:285-302.
Similar publications
Sorry the service is unavailable at the moment. Please try again later.
This website uses cookies to improve user experience. Read more
Save & Close
Accept all
Decline all
Show detailsHide details
Cookie declaration
About cookies
Strictly necessary
Performance
Strictly necessary cookies allow core website functionality such as user login and account management. The website cannot be used properly without strictly necessary cookies.
This cookie is used by Cookie-Script.com service to remember visitor cookie consent preferences. It is necessary for Cookie-Script.com cookie banner to work properly.
Performance cookies are used to see how visitors use the website, eg. analytics cookies. Those cookies cannot be used to directly identify a certain visitor.
Used to store the attribution information, the referrer initially used to visit the website
Cookies are small text files that are placed on your computer by websites that you visit. Websites use cookies to help users navigate efficiently and perform certain functions. Cookies that are required for the website to operate properly are allowed to be set without your permission. All other cookies need to be approved before they can be set in the browser.
You can change your consent to cookie usage at any time on our Privacy Policy page.