Discussion on “Cold metal working” at the Coventry Section of the Institution

1932 ◽  
Vol 11 (4) ◽  
pp. 156
Author(s):  
Drane ◽  
Povey ◽  
Newbold ◽  
R.H. Jones ◽  
Macnab ◽  
...  
Keyword(s):  
1932 ◽  
Vol 11 (4) ◽  
pp. 150
Author(s):  
H.G. Povey
Keyword(s):  

Early China ◽  
1981 ◽  
Vol 6 ◽  
pp. 4-30 ◽  
Author(s):  
Noel Barnard

AbstractThe existence of certain types of Lung-shan pottery vessels and early Shang bronzes based upon supposed wrought metal prototypes continues to lead some scholars to the conclusion that these cultures had knowledge of sheet metal, smithy techniques. An analysis of such features as the tubular spout, projecting ledges, imitation “rivets,” and imitation folded rims leads to the conclusion that their presence is accounted for either by the versatility of the Neolithic potters, by the requirements of metal casting techniques, or by decorative considerations; it need not, and frequently cannot, be explained in terms of sheet metal prototypes. The article also considers the nature and significance of various cold metal working techniques, such as annealing. In the view of the wrought-metal advocates, these techniques would have had to have been discarded and forgotten by the early Chinese metal workers in favor of direct casting in piece-mold assemblies. This is highly unlikely.


Author(s):  
William P. Sharp ◽  
Robert W. Roberson

The aim of ultrastructural investigation is to analyze cell architecture and relate a functional role(s) to cell components. It is known that aqueous chemical fixation requires seconds to minutes to penetrate and stabilize cell structure which may result in structural artifacts. The use of ultralow temperatures to fix and prepare specimens, however, leads to a much improved preservation of the cell’s living state. A critical limitation of conventional cryofixation methods (i.e., propane-jet freezing, cold-metal slamming, plunge-freezing) is that only a 10 to 40 μm thick surface layer of cells can be frozen without distorting ice crystal formation. This problem can be allayed by freezing samples under about 2100 bar of hydrostatic pressure which suppresses the formation of ice nuclei and their rate of growth. Thus, 0.6 mm thick samples with a total volume of 1 mm3 can be frozen without ice crystal damage. The purpose of this study is to describe the cellular details and identify potential artifacts in root tissue of barley (Hordeum vulgari L.) and leaf tissue of brome grass (Bromus mollis L.) fixed and prepared by high-pressure freezing (HPF) and freeze substitution (FS) techniques.


2001 ◽  
Author(s):  
K. Bartlett ◽  
J. Phipps ◽  
K. Kulhankova ◽  
P. Thorne
Keyword(s):  

Author(s):  
M Pal

The marine environment is hostile to most engineering materials, a combination of in-service wear and exposure to marine environment leads to an accelerated material degradation.  Insufficient or poor protection of the substrates further assists the accelerated material degradation in marine environment. There is a direct relationship between the material-state of a ship and its operational capability, readiness, and service life.  The current state-of-the-art practice is to use paint-based coatings to maintain the material-state of ships.  However, the protection offered by paint coatings is usually brief due to inherent permeability and low damage tolerance of these coatings.  For this reason, the paint coatings require renewal at regular intervals, typically less than 5-years, to maintain a minimum level of protection from the marine environment.  The need for regular painting of ships results in a significant negative impact on the through-life availability, operational capability/readiness, and the cost of maintenance/operation of naval ships.  Therefore, the fleet owners and operators should look beyond the conventional paint-based coatings to achieve significant breakthrough improvements in maintaining and enhancing the material-state of naval ships. Metallic coatings, if selected and applied appropriately, will outperform the paint coatings in the marine environment.  Historically, the cost and performance of metallic coatings, mainly thermal metal spray (TMS) coatings, prevented their widespread use in the marine industry.  The TMS coatings also have their own inherent application and performance related limitations that are widely reported in the literature.  However, the cold metal spray (CMS) coating process can overcome the application and performance related limitations that are typically associated with the TMS coatings, therefore creating an opportunity for widespread use of metallic coatings in shipbuilding and fleet upkeep/maintenance. In this paper, the ability of low-pressure (LP-CMS) coatings to repair and reclaim damaged marine components, and application of functional coatings to improve in-service damage tolerance of the damaged/new components is investigated.  The results of the investigation show that two LP-CMS coatings, Al-alloy and CuZn-alloy, can be used to repair and preserve both new and damaged components.  The accelerated salt-spray and natural immersion corrosion testing of the LP-CMS coatings showed that each coating will be better suited to a particular operational environment, i.e. CuZn-alloy coating performed well in both immersion and atmospheric corrosion environments, whereas Al-alloy coating performed well only in atmospheric corrosion environment. 


Sign in / Sign up

Export Citation Format

Share Document