ISSN:0021-8871    

DOI:10.1002/jctb.5010101108

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractLoss of adhesion between a bituminous binder and stone in the presence of water may take place by the retraction of the binder. It is suggested that this mechanism only operates when the viscosity of the binder is low. When loss of cohesion occurs in a carpet it more normally originates from the accumulation of water at the binder/stone interface leading to a condition in which the binder may be peeled cleanly away from the stone surface. This detachment occurs equally with bitumens and tars and, under traffic stresses, may lead to the loss of cohesion which, although comparatively rarely, sometimes leads to surface disintegration.Pretreatment of the mineral surface with certain metal salts may delay for several months the initial state of detachment, whereas this state cannot be prevented or delayed for more than a few days by the addition of wetting additives to the binder. Such additives, however, may modify the subsequent degree of detachment and very much reduce the loss of cohesion which may follow under the action of traffic. Loss of cohesion in these circumstances can also be reduced by the presence in the binder of components which have no possitive wetting tendency but confer a certain interfacial rigidity.It is tentatively suggested that the condition of detachment is due to the absorption of water into the silicate lattice to give a weakened gel‐like structure and cause a rise in pH value at the surface of the mineral. This rise in pH value is thought to be responsible for the inability of wetting additives to prevent the initial state of detachment being reached.Liability to detach is determined by the chemical nature of the aggregate and may not occur with minerals containing high proportions of more basic components particularly those containing iron. Under most conditions of stressing, the bond strength in the detached state is equivalent to that in the dry state although after prolonged immersion the resistance to tangential stresses may be relatively small. When the system dries out, reattachment may occur. These factors may help to explain why there is no direct relationship between the initial state of detachment and behaviour in practic

ISSN:0021-8871    

DOI:10.1002/jctb.5010101102

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractPicrite propellants (N, NQ, SPCG) were artificially aged at 65° and the rate and manner of decomposition were followed by separation and analyses of the products derived from the stabiliser due to its combination with nitrogen oxides. An SC formulation which does not contain picrite was treated in a similar manner.The total amount of degradation, as evidenced by the formation of nitrosated and nitrated derivatives of centralite, was less in the picrite propellants. In the latter, a higher proportion of nitrated products to nitrosated products was recovered while in the SC composition nitrosation was the major reaction. Direct nitration of the stabiliser as well as rearrangement of nitrosamines to nitro compounds is shown to be more active in the picrite propellants during ageing

ISSN:0021-8871    

DOI:10.1002/jctb.5010101103

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractCapacity measurements obtained with an a.c. bridge have been used to determine the thickness of non‐porous oxide films on iron and aluminium surfaces, and for showing the effect of both the solvent action of aqueous solutions and electrochemical processes on the thickness of these films.These measurements could not be used, however, to detect the increase of permeability of the oxide film on aluminium placed in solutions containing chloride; electrode potential measurements were used in this case.Measurements of capacity and of potential vs. time were used to show formation of pores through oxide film

ISSN:0021-8871    

DOI:10.1002/jctb.5010101104

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractInvestigations on the composition and stability of the solid barium zincates have shown that the BaO‐ZnO‐H2O system is complex. At 90°, the following stable solid phases exist: Ba(OH)2,H2O; ZnO; BaO,ZnO,2H2O; BaO,ZnO,3H2O; 2BaO,ZnO,3H2O; 2BaO,ZnO,7H2O and possibly further hydrates of BaO,ZnO and 2BaO,ZnO.At 70°, BaO,ZnO,2H2O; BaO,ZnO,3H2O; 2BaO,ZnO,7H2O, Ba(OH)2,8H2O and ZnO are the stable solid phases. The beginning of the transition interval is 70° for the 2BaO,ZnO,7H2O compound which is unstable below this temperature.X‐ray diffraction patterns have been obtained for BaO,ZnO,2H2O and the tr

ISSN:0021-8871    

DOI:10.1002/jctb.5010101105

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractThe exposure of sets of small test specimens in 45 different atmospheres, principally indoors in factories, has provided a measure of the relative corrosiveness of the atmospheres in such places. The test specimens were of bare low‐alloy and mild steels and mild steel sprayed with aluminium or with zinc.The most corrosive indoor atmospheres investigated were those where large quantities of acids were used, and those of a bleach‐house, a plating shop and a glue extraction plant. Several were more corrosive than the atmosphere outdoors at Sheffield, particularly towards the metal coatings. Although aluminium protected the steel better than did zinc when freely exposed outdoors in industrial atmospheres, a zinc coating was much superior to an aluminium one in many of the indoor atmospheres. High humidity was associated with rapid corrosion rates but corrosion was slow in relatively clean but humid atmospheres, such as were found in a laundry, domestic kitchens and bathro

ISSN:0021-8871    

DOI:10.1002/jctb.5010101106

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

摘要:

AbstractTar has been recovered from a number of surface dressings at intervals during the first year of their life and the changes in viscosity determined. A method is described for determining the contributions of oxidation and loss of oils to the observed hardening, and the results for one pair of dressings are given. The hardening of the tar was mainly due to loss of oils, oxidation accounting for about one quarter of the effect. Tars derived from a high‐aromatic crude only have been examined; other tars are to be tested in a similar wa

ISSN:0021-8871    

DOI:10.1002/jctb.5010101107

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010101101

出版商:John Wiley&Sons, Ltd    

年代:1960

数据来源: WILEY