Charbonneau J E
National Food Processors Association, Food Chemistry and Packaging Dept., Washington, DC 20005, USA.
Scanning. 1997 Oct;19(7):512-8. doi: 10.1002/sca.4950190710.
Scanning electron microscopy (SEM) and x-ray microanalysis (EDS) were used to investigate stress corrosion cracking (SCC) in plain tinplate food cans, product discoloration, filiform corrosion, pitting/perforation corrosion, and loss of coating adhesion in enameled food cans. Intergranular SCC of uncoated tinplate occurred in canned pineapple juice. This is a rare occurrence in acid food products. The fracture developed in the can headspace only at the product line/metal interface by an interaction of the detinned metal surface with stress-inducing compounds in the product. Black discoloration of rice granules in the can headspace of a chicken and rice product was caused by the formation of metal sulfides. The source of the metal contamination was traced to metallic dirt in the coating on the tin-free-steel end. Blackening of light tan-colored olives and brine occurred after 1 year of storage in enameled tinplate containers as a result of pitting corrosion at the side seam weld. The cause of the pitting was a defective side seam stripe which failed to protect the weld. A perforation problem occurred at the score line of aluminum-tinplate bimetallic cans. The failure was caused by the high chloride content of the fruit product. Filiform corrosion resulted in perforations that occurred on the outside surfaces of two-piece tin-free steel cans packed with tuna. The cause of the corrosion was related to scratch defects in the exterior coating and the presence of chloride and sulfate cannery residues in the corroded areas. An enamel adhesion failure developed inside two-piece tin-free steel cans that contained mushrooms. Wrinkles in the coating which were introduced during can manufacture were cracked. The fractures were pathways for product-steel interaction which resulted in container failure.
采用扫描电子显微镜（SEM）和X射线微分析（EDS）研究了马口铁食品罐中的应力腐蚀开裂（SCC）、产品变色、丝状腐蚀、点蚀/穿孔腐蚀以及搪瓷食品罐中涂层附着力丧失等问题。未涂层马口铁的晶间应力腐蚀开裂发生在菠萝汁罐头中。这在酸性食品中很少见。罐顶隙处的断裂仅在生产线/金属界面处发生，是由于脱锡金属表面与产品中应力诱导化合物相互作用所致。鸡肉米饭产品罐顶隙中米粒变黑是由金属硫化物的形成引起的。金属污染的来源可追溯到无锡钢罐盖上涂层中的金属污垢。浅棕橄榄和盐水在搪瓷马口铁容器中储存1年后变黑，这是侧缝焊缝处点蚀的结果。点蚀的原因是侧缝条纹有缺陷，未能保护焊缝。铝马口铁双金属罐的刻痕线处出现了穿孔问题。故障是由水果产品中高氯含量引起的。丝状腐蚀导致了装有金枪鱼的两片式无锡钢罐外表面出现穿孔。腐蚀的原因与外涂层的划痕缺陷以及腐蚀区域中存在的氯化物和硫酸盐罐头厂残留物有关。装有蘑菇的两片式无锡钢罐内部出现了搪瓷附着力失效。罐制造过程中引入的涂层皱纹出现了开裂。这些裂缝是产品与钢相互作用的通道，导致容器失效。
