{"id":8696,"date":"2024-08-08T18:31:54","date_gmt":"2024-08-08T10:31:54","guid":{"rendered":"https:\/\/xzfastener.com\/?p=8696"},"modified":"2026-06-29T18:33:17","modified_gmt":"2026-06-29T10:33:17","slug":"screw-surface-finishes-zinc-black-oxide-dacromet-and-passivation","status":"publish","type":"post","link":"https:\/\/xzfastener.com\/vi\/screw-surface-finishes-zinc-black-oxide-dacromet-and-passivation\/","title":{"rendered":"B\u1ec1 m\u1eb7t ho\u00e0n thi\u1ec7n tr\u1ee5c v\u00edt: K\u1ebdm, \u00d4x\u00edt \u0111en, Dacromet v\u00e0 Th\u1ee5 \u0111\u1ed9ng"},"content":{"rendered":"

Many screw problems start with a finish choice that looked simple on the purchase order.<\/p>\n\n\n\n

A buyer asks for \u201czinc plated screws.\u201d The end user expects outdoor corrosion resistance. A maintenance team asks for black oxide because the sample was black. The application actually needs oil, controlled storage, or a zinc flake coating. Stainless screws are ordered with \u201cpassivation\u201d added as if it were a coating.<\/p>\n\n\n\n

These are common misunderstandings. Surface finish is not decoration. It affects corrosion resistance, friction, assembly behavior, appearance, storage life, and sometimes fastener strength.<\/p>\n\n\n\n

The Main Finishes Buyers Compare<\/h2>\n\n\n\n

So s\u00e1nh th\u1ef1c t\u1ebf<\/h3>\n\n\n\n
K\u1ebft th\u00fac<\/th>S\u1eed d\u1ee5ng chung<\/th>\u01afu \u0111i\u1ec3m ch\u00ednh<\/th>H\u1ea1n ch\u1ebf ch\u00ednh<\/th><\/tr><\/thead>
M\u1ea1 k\u1ebdm<\/td>General carbon steel screws<\/td>Economical corrosion protection<\/td>Limited outdoor life unless specified well<\/td><\/tr>
Oxit \u0111en<\/td>Tools, indoor machinery, appearance parts<\/td>Thin finish, dark appearance<\/td>Low corrosion resistance without oil<\/td><\/tr>
Dacromet \/ m\u1ea3nh k\u1ebdm<\/td>Automotive, outdoor, high-corrosion assemblies<\/td>Stronger corrosion protection, no electroplating hydrogen risk in many systems<\/td>Higher cost, coating thickness affects fit<\/td><\/tr>
Passivation<\/td>Stainless steel screws<\/td>Improves stainless surface cleanliness<\/td>Not a plated coating; does not add thickness<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

For project buyers comparing options, XZ Fastener\u2019s \u1ed1c v\u00edt tr\u00e1ng<\/a> category is a useful place to frame finish discussions before finalizing an RFQ.<\/p>\n\n\n\n

m\u1ea1 k\u1ebdm<\/h2>\n\n\n\n

Where It Works<\/h3>\n\n\n\n

Zinc plating is the most common finish for carbon steel screws. It is widely used for indoor equipment, furniture hardware, light machinery, electrical brackets, and general replacement parts.<\/p>\n\n\n\n

Common references include ASTM B633, ASTM F1941\/F1941M, and ISO 4042, depending on market and fastener type.<\/p>\n\n\n\n

Ng\u01b0\u1eddi mua th\u1eadn tr\u1ecdng<\/h3>\n\n\n\n

Zinc plating is not one single performance level. Thickness, chromate type, sealers, and salt spray requirements must be defined.<\/p>\n\n\n\n

A vague \u201czinc plated\u201d order can create disputes. Blue-white zinc, yellow zinc, black zinc, and trivalent systems may all look different and perform differently.<\/p>\n\n\n\n

For high-strength carbon steel screws, electroplating also raises hydrogen embrittlement concerns. Baking requirements should be reviewed before production, especially for higher property classes.<\/p>\n\n\n\n

Oxit \u0111en<\/h2>\n\n\n\n

Where It Works<\/h3>\n\n\n\n

Black oxide is often selected for appearance, reduced light reflection, and very thin dimensional impact. It is common on socket screws, tool parts, machine components, and indoor equipment.<\/p>\n\n\n\n

It is not a strong corrosion finish by itself.<\/p>\n\n\n\n

Ng\u01b0\u1eddi mua th\u1eadn tr\u1ecdng<\/h3>\n\n\n\n

Black oxide normally needs oil or wax to provide short-term protection. If parts are shipped overseas, stored in humid warehouses, or handled with bare hands, rust may appear faster than expected.<\/p>\n\n\n\n

This is where many claims begin. The finish was technically correct, but the storage condition was not suitable.<\/p>\n\n\n\n

For buyers working with carbon steel screw programs, it helps to separate black oxide requirements from zinc or zinc flake requirements in the purchasing file. Related \u1ed1c v\u00edt th\u00e9p carbon<\/a> should be reviewed by grade, finish, and packaging together.<\/p>\n\n\n\n

Dacromet v\u00e0 l\u1edbp ph\u1ee7 v\u1ea3y k\u1ebdm<\/h2>\n\n\n\n

Where It Works<\/h3>\n\n\n\n

Dacromet is often used as a familiar market term, though many current projects specify zinc flake coatings more broadly. These finishes are common in automotive parts, outdoor equipment, brackets, solar structures, machinery, and high-corrosion assemblies.<\/p>\n\n\n\n

Common references may include ISO 10683 or project-specific coating specifications.<\/p>\n\n\n\n

Ng\u01b0\u1eddi mua th\u1eadn tr\u1ecdng<\/h3>\n\n\n\n

Zinc flake systems can provide better corrosion resistance than standard zinc plating, but they are not interchangeable with every screw. Coating thickness can affect thread fit, recess engagement, and assembly torque.<\/p>\n\n\n\n

Also, salt spray hours should not be treated as a direct guarantee of field life. Real service includes water, heat, chemicals, vibration, and installation damage.<\/p>\n\n\n\n

Passivation<\/h2>\n\n\n\n

Where It Works<\/h3>\n\n\n\n

Passivation is used for stainless steel screws. It removes free iron contamination and helps restore the stainless surface condition after forming, machining, or handling.<\/p>\n\n\n\n

Common references include ASTM A967 and ASTM A380.<\/p>\n\n\n\n

Ng\u01b0\u1eddi mua th\u1eadn tr\u1ecdng<\/h3>\n\n\n\n

Passivation is not a coating like zinc. It does not build a protective metal layer. It will not make a poor stainless grade behave like a higher alloy.<\/p>\n\n\n\n

For example, A2 stainless and A4 stainless have different corrosion behavior. Passivation helps the surface, but material selection still matters.<\/p>\n\n\n\n

How to Specify Screw Finishes Correctly<\/h2>\n\n\n\n

A Better RFQ Checklist<\/h3>\n\n\n\n

Before ordering, define:<\/p>\n\n\n\n

    \n
  1. Screw standard and size.<\/li>\n\n\n\n
  2. L\u1edbp v\u1eadt ch\u1ea5t v\u00e0 thu\u1ed9c t\u00ednh.<\/li>\n\n\n\n
  3. Finish type.<\/li>\n\n\n\n
  4. Coating thickness or class.<\/li>\n\n\n\n
  5. Color requirement if appearance matters.<\/li>\n\n\n\n
  6. Salt spray requirement, if applicable.<\/li>\n\n\n\n
  7. Baking requirement for high-strength parts.<\/li>\n\n\n\n
  8. Lubrication or sealer requirement.<\/li>\n\n\n\n
  9. Packaging and humidity protection.<\/li>\n\n\n\n
  10. Inspection documents required.<\/li>\n<\/ol>\n\n\n\n

    For DIN and ISO descriptions, the H\u01b0\u1edbng d\u1eabn ti\u00eau chu\u1ea9n chi ti\u1ebft si\u1ebft ch\u1eb7t DIN v\u00e0 ISO<\/a> can help buyers align screw standards before coating is confirmed.<\/p>\n\n\n\n

    L\u1eddi khuy\u00ean cu\u1ed1i c\u00f9ng<\/h2>\n\n\n\n

    Do not choose screw surface finishes by color alone.<\/p>\n\n\n\n

    Choose zinc when economical indoor protection is enough. Choose black oxide when appearance and thin finish matter, but corrosion exposure is low. Choose Dacromet-style zinc flake when corrosion resistance and coating behavior justify the cost. Choose passivation for stainless steel surface cleanliness, not as a substitute for the right stainless grade.<\/p>\n\n\n\n

    For project-specific review, buyers can li\u00ean h\u1ec7 XZ Fastener<\/a> with drawings, material grade, finish requirements, quantity, packaging, and inspection expectations before production.<\/p>","protected":false},"excerpt":{"rendered":"

    Many screw problems start with a finish choice that looked simple on the purchase order. A buyer asks for \u201czinc plated screws.\u201d The end user expects outdoor corrosion resistance. A maintenance team asks for black oxide because the sample was black. The application actually needs oil, controlled storage, or a zinc flake coating. Stainless screws […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[479],"tags":[508],"class_list":["post-8696","post","type-post","status-publish","format-standard","hentry","category-fastener-knowledge-library","tag-screw-knowledge"],"acf":[],"_links":{"self":[{"href":"https:\/\/xzfastener.com\/vi\/wp-json\/wp\/v2\/posts\/8696","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/xzfastener.com\/vi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/xzfastener.com\/vi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/xzfastener.com\/vi\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/xzfastener.com\/vi\/wp-json\/wp\/v2\/comments?post=8696"}],"version-history":[{"count":1,"href":"https:\/\/xzfastener.com\/vi\/wp-json\/wp\/v2\/posts\/8696\/revisions"}],"predecessor-version":[{"id":8697,"href":"https:\/\/xzfastener.com\/vi\/wp-json\/wp\/v2\/posts\/8696\/revisions\/8697"}],"wp:attachment":[{"href":"https:\/\/xzfastener.com\/vi\/wp-json\/wp\/v2\/media?parent=8696"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/xzfastener.com\/vi\/wp-json\/wp\/v2\/categories?post=8696"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/xzfastener.com\/vi\/wp-json\/wp\/v2\/tags?post=8696"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}