Underwater bonding

One of the most promising innovations in recent years is the development of hydrophobic Sacrificial Pretreatment Technology (SPT), in conjunction with hydrophobic cold-cure epoxies, to enable underwater bonding(70,83). The energetically-favourable conditions for bonding are established underwater by the application of a water-repellant preferred contaminant to a cleaned or blasted steel... 

Shafiq, Z., Cui, J. X., Pastor-Perez, L., SAN Miguel, V, Gropeanu, R. A., Serrano, C. and DEL Campo, A. (2012). Bioinspired underwater bonding and debonding on demand. Angewauufte Chemie-Intemational Edition, 51,4332-4335. 

Typical uses include the production of non-dispersible underwater concrete and reduction of the accumulation of bleed water in mass concrete placed in deep forms. Consequently, AWAs are useful in mass concrete work because they prevent the formation of laitance on the surface of the concrete and thereby reduce the excessive cleaning between successive lifts. The admixtures also reduce the voids formed under horizontal reinforcing bars. Therefore, bond to steel increases and potential corrosion problems are reduced. The admixtures are also used in conjunction with WRAs in oil-well cementing grouts to reduce pipeline friction and rapid water loss and grouting of pre- and post-tensioned concrete ducts [47]. New valves and control devices under development in Europe and Japan used in conjunction with AWA will likely advance the field on underwater concrete. 

Mortar (sometimes called cement) is used to bond surfaces like bricks together, but also for plastering walls. Historically, it has been composed variously of lime, sand, clay, volcanic rock and ash, brick dust, and potsherds. Early lime mortars that set simply by reaction between the lime and carbon dioxide in the air offered little protection from deleterious effects of water to the structure. Aggregate mortars that incorporatepozzolans and silicates, which react to bond with calcium, do not need C02, and some can even set underwater. These are called hydraulic mortars, and offer durability in weather, but are less suitable for situations where plasticity is needed, as in restoration projects, for example. 

Sacrificial pretreatment, by acting as a hydrophobic preferred contaminant to enable bonding underwater(70). 

Extensive adhesive testing has been reported for a variety of systems aimed at widely different bonding applications. Aircraft is represented with numerous studies of which selected references are representative for nitrile rubber modified adhesive systems (54-56). Underwater curing adhesives (57), construction adhesives (58), intumescent adhesives (59) and materials related to improved adhesion or adhesives in electrical/electronic circuitry fabrication (60-62) serve to show the wide latitude of nitrile rubber modified adhesive proliferation. ... 

One of the most difficult adhesive problems involves the underwater sonar systems. Elastomers (29) (Neoprene rubbers) are adhered to metals with adhesives. The applications include cable sheath, vibration isolator and damper, acoustic absorber, sound reflector, sonar-dome window, and transducer boot. A poor bond at the Neoprene-steel interface could easily lead to saltwater penetration and corrosion, which eventually causes the failure of the sonar dome. 

In the future, underwater acoustic system research should be designed to identify the mechanisms of bond degradation and to develop accelerated life testing methods and long-term predictive capability. 

Perhaps, the earlier materials found to have a useful capacity for adhesive bonding underwater depended upon the use of a stoichiometric excess of water-scavenging polyamide hardener in an epoxide-based adhesive. This approach can lead to the production of effective joints in the short term, but formulations of this type, which are hydrophilic in the uncured state, are also likely to absorb significant amounts of water in the cured condition. It is a widely accepted view that the extent of joint weakening in susceptible joints, quite apart from the consequences of plasticization, is a function of the water-uptake characteristics of the adhesive (see Glass transition temperature). The consequence is therefore likely to be that such joints will show poor durability in the presence of water, when rapid uptake of water may lead to equally rapid degradation of both cohesive and interfacial properties (see Durability fundamentals). 

Gadget Underwater manta ray cloak, used by Bond in Licence to Kill. 

Gadget Lotus Esprit sports car that turns into a submarine, complete with mines, missiles, underwater ink jets, and self-destruct mechanism, that Bond used in The Spy Who Loved Me and For Your Eyes Only. 

Crowther, Bosley. Screen 007 s Underwater Adventures Connery Plays Bond in Thunderball . New York Times. 22 Dec. 1965. . 

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