JPS6229510B2 - - Google Patents
Info
- Publication number
- JPS6229510B2 JPS6229510B2 JP3505083A JP3505083A JPS6229510B2 JP S6229510 B2 JPS6229510 B2 JP S6229510B2 JP 3505083 A JP3505083 A JP 3505083A JP 3505083 A JP3505083 A JP 3505083A JP S6229510 B2 JPS6229510 B2 JP S6229510B2
- Authority
- JP
- Japan
- Prior art keywords
- chemical conversion
- steel sheet
- treatment
- cold
- conversion treatment
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000000126 substance Substances 0.000 claims description 77
- 238000006243 chemical reaction Methods 0.000 claims description 53
- 229910000831 Steel Inorganic materials 0.000 claims description 26
- 239000010959 steel Substances 0.000 claims description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 14
- 239000010960 cold rolled steel Substances 0.000 description 24
- 239000013078 crystal Substances 0.000 description 18
- 238000005260 corrosion Methods 0.000 description 17
- 230000007797 corrosion Effects 0.000 description 17
- 239000011248 coating agent Substances 0.000 description 14
- 238000000576 coating method Methods 0.000 description 14
- 238000007747 plating Methods 0.000 description 14
- 238000000034 method Methods 0.000 description 13
- 230000015572 biosynthetic process Effects 0.000 description 12
- 229910019142 PO4 Inorganic materials 0.000 description 10
- 239000000463 material Substances 0.000 description 10
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 10
- 239000010452 phosphate Substances 0.000 description 10
- 238000005554 pickling Methods 0.000 description 10
- 239000003973 paint Substances 0.000 description 9
- 238000001816 cooling Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 238000007739 conversion coating Methods 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 238000009713 electroplating Methods 0.000 description 6
- 238000000137 annealing Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 239000000523 sample Substances 0.000 description 5
- LRXTYHSAJDENHV-UHFFFAOYSA-H zinc phosphate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O LRXTYHSAJDENHV-UHFFFAOYSA-H 0.000 description 5
- 229910000165 zinc phosphate Inorganic materials 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 238000000151 deposition Methods 0.000 description 4
- 238000004070 electrodeposition Methods 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 230000001590 oxidative effect Effects 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 125000002091 cationic group Chemical group 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 235000014413 iron hydroxide Nutrition 0.000 description 3
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000011701 zinc Substances 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 229920000298 Cellophane Polymers 0.000 description 1
- XTEGARKTQYYJKE-UHFFFAOYSA-M Chlorate Chemical class [O-]Cl(=O)=O XTEGARKTQYYJKE-UHFFFAOYSA-M 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 229910001335 Galvanized steel Inorganic materials 0.000 description 1
- 241000080590 Niso Species 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000008397 galvanized steel Substances 0.000 description 1
- 239000012943 hotmelt Substances 0.000 description 1
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 150000002826 nitrites Chemical class 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000006748 scratching Methods 0.000 description 1
- 230000002393 scratching effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000010421 standard material Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/78—Pretreatment of the material to be coated
Landscapes
- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Treatment Of Metals (AREA)
Description
この発明は化成処理性にすぐれた表面処理鋼板
に関する。
自動車用鋼板は一般に、実際使用に際してはプ
レス成形などの加工を行つた後、塗料下地処理と
しての化成処理（例えばリン酸塩処理）を施し、
しかる後その上に例えばカチオン電着塗装を施し
て最終用途に使用されるが、前記電着塗装の塗膜
が良好な塗装耐食性を得るためには、まず下地処
理において良好な化成皮膜を得ることが必要不可
欠の条件となる。この良好な化成皮膜を得るため
には、素材の冷延鋼板表面が化成皮膜結晶の核発
生や成長を阻害しないような良好な性状（化成処
理性にすぐれた性状）を有していることが必要と
なる。
さて、自動車用鋼板として用いられる冷延鋼板
は、従来は連続焼鈍後における冷却を無酸化雰囲
気でのガスジエツトクール等の方法で行つていた
ので、化成皮膜の形成に有利とされるMn等の表
面濃化層が存在するとともに水酸化鉄等の腐食生
成物の付着等が無いため、化成処理性にすぐれた
鋼板であつた。しかし最近、上記連続焼鈍におけ
るヒートサイクルの合理化を図るため、無酸化雰
囲気でのガスジエツトクールに代えて水冷または
気水冷却の方法を採用する傾向にある。この場
合、冷却過程が酸化性雰囲気となるため表面に酸
化膜が生成し、従つてこの酸化膜を除去するため
の例えば酸洗処理が必要となる。この酸洗処理を
行つた鋼板は、上記Mn濃化層が除去されたり、
また酸洗残渣（水酸化鉄）の表面吸着、水錆の発
生等があつて表面性状が悪化し化成処理性が劣化
してきている。
また冷延鋼板を自動車車体等に用いる場合、車
体腐食が安全上の問題となるが、近時特に自動車
外板で腐食を激しく受ける片面のみを耐食性にす
ぐれたメツキ被覆面とし、他面を裸面のままとし
て車体腐食の軽減を図るようにした片面メツキ鋼
板が用いられるようになつてきた。
片面メツキ鋼板としては、電気メツキ法と溶融
メツキ法の２種類の製造方法があるが、電気メツ
キ法の場合は前処理として酸洗が行われ、また多
くの場合酸性浴である電気メツキ浴を通過して酸
洗効果を受けるため、非メツキ面の冷延鋼板の化
成処理性は劣化する。また溶融メツキ法の場合
は、高温状態で溶融メツキ浴中から大気中に出て
くるため非メツキ面の酸化は避け難く、このため
メツキ終了後酸洗処理が必要となり、上記と同様
に非メツキ面の化成処理性は劣化する。近年特に
Fe系またはFe−Zn系合金電気メツキが一般的と
なりつつあるが、この場合酸性メツキ浴中に多量
のFe3+イオンを含有しているため、非メツキ面
はメツキ槽中の浸漬により酸焼けピツテイング状
態を呈しており、化成処理性が極めて劣悪になつ
ている。また電気Znメツキ法によるものもある
が、この場合も高電流密度操業の傾向が進むにつ
れて腐食性の強い塩化浴が使用されるため、非メ
ツキ面側に極めて激しい溶解が起り、このため化
成処理性が極めて劣悪になつている。また特にメ
ツキ浴槽内での浸漬時間の長いたて型メツキ槽を
用いた場合は、よこ型メツキ槽を用いた場合に比
較して非メツキ面の化成処理性の劣化は極めて激
しくなり深刻な事態を生じるに至つている。近
年、自動車・家電業界において高張力冷延鋼板の
使用比率が高まつているが、高張力冷延鋼板は、
一般冷延鋼板に比較して、一層、酸性液による浸
漬で化成処理性が劣悪となるので問題である。
また一方、自動車用鋼板に化成処理を施す場合
は、前述の如く自動車メーカー側で素材鋼板を成
形加工した後、化成処理量産ラインで化成処理す
るのが通例であるが、この場合例えばリン酸亜鉛
処理液中の浴成分（Zn2+、Fe2+、硝酸塩、亜硝
酸塩、塩素酸塩等の酸化促進剤）の経時変化が起
り、狭少な浴管理条件範囲から外れるトラブルが
頻発し易いために、浴成分の変動に対しても常に
すぐれた化成処理性を維持できるような対応性に
すぐれた冷延鋼板が望まれていた。
本発明は上記酸洗を受けた冷延鋼板面ならびに
片面メツキ鋼板の非メツキ面において化成処理性
の劣化がなく、化成処理量産ラインにおいて浴成
分の変動に対する対応性にすぐれた化成処理性が
得られるような表面処理鋼板を提供しようとする
ものである。
化成処理性に劣る冷延鋼板表面の改善を図るこ
とを目的として、冷延鋼板表面に金属Niを0.3〜
10mg／ｄm2付着させる方法が特開昭56−116883号
公報で開示されている。この発明によれば、処理
条件の安定したリン酸塩処理試験においては確か
に化成処理性（化成皮膜の結晶サイズ、付着量
等）や塗装耐食性の向上効果は得られる。しかし
金属Niを付着した冷延鋼板表面は、表面析出し
た金属Niの局部電池の構成作用が極めて強く、
化成処理反応に対して極めて敏感な表面状態とな
つている。
上述したようにリン酸亜鉛処理量産ラインにお
ける化成処理作業においては、浴成分の経時変化
が生じ易いが、浴成分中の酸化促進剤の添加量や
金属Niの付着量は極めて微量であるためそれら
の量の変化の割合は特に大きくなり勝ちである。
従つてこれらの量の変化は金属Niを付着した冷
延鋼板の化成処理反応に敏感に反映され、これら
の量が多くなると化成処理反応速度（化成皮膜形
成の速度）が過大となつて、化成皮膜中に塗装耐
食性に悪い影響を与えるホーパイトの粗な針状結
晶が多く生じ易くなる。公知の如く、リン酸亜鉛
処理における化成皮膜は、ホーパイト結とフオス
フオフイライト結晶（緻密な柱状結晶）との複合
リン酸亜鉛皮膜で構成されており、この内ホーパ
イト結晶が多くなると塗装耐食性が劣化する性質
を有しているので、金属Niを付着させた冷延鋼
板は対応性が敏感すぎて、化成処理量産ライン等
実際面で用いるには必ずしも適しているとはいい
難い。
そこで本発明者らは、良好な化成処理性が得ら
れるとともに、化成処理の浴成分等の経時変化に
対して金属Niのように化成処理反応が敏感に反
映しないような性質を持つ化成処理性にすぐれた
表面処理鋼板の開発を意図して、まず対象として
金属Niより反応が敏感でない半電導性の性質を
有するNi酸化物・Ni水酸物を表面に付着させた
冷延鋼板を考えて種々実験研究を重ねた。
本発明者らは、化成処理性にすぐれた表面処理
鋼板の標準材として、無酸化ガス雰囲気中で焼鈍
後の冷却を行つた後0.5％圧下率の調質圧延工程
を経たアルミキルド冷延鋼板（板厚0.8mm）を用
い、これを酸洗→水洗→乾燥処理して化成処理性
を劣化させた冷延鋼板にNi酸化物・Ni水酸物を
Ni元素重量換算で30mg／m2付着させて供試材(D)
を得た。また比較のため上記標準材の冷延鋼板
(A)、標準延鋼板(A)を酸洗処理した冷延鋼板(B)、前
記冷延鋼板(B)に金属Ni15mg／m2付着させた鋼板
(C)を供試材とした。上記各供試材(A)(B)(C)(D)をリン
酸亜鉛処理液（ボンデライト3030）による浸漬時
間を種々に変えた浸漬処理でリン酸塩付着量およ
び化成処理反応速度（化成処理皮膜形成が完了す
るまでの所要時間）を調査した。結果を第１図に
示す。第１図は上記供試材(A)(B)(C)(D)の化成反応時
間とリン酸塩付着量との関係を示す図である。
図に見る如く、供試材(A)(C)(D)はいずれも２分程
度で略々化成皮膜の形成が完了し化成処理性にす
ぐれていることが示され、これに対し供試材(B)は
化成処理性に劣つていることが示された。また化
成処理反応速度については、供試材(C)が最も速
く、供試材(D)は供試材(A)と略々同等の成積が示さ
れ、供試材(B)に比較して顕著な化成処理性の向上
が示された。
また化成処理反応の敏感性については、供試材
(C)は金属Niの付着量が多くなると、化成処理反
応速度はたちまち過大となり、化成結晶にホーパ
イト分の多い粗な針状結晶が多く生じるようにな
るが、これに対し供試材(D)はNi酸化物・Ni水酸
化物の付着量が多くなつても化成処理反応速度は
殆んど変化を示さず、フオスフオフエライト分の
多い緻密な結晶が得られ、供試材(C)よりははるか
に対応性が鈍感であつた。
これらの研究結果をふまえてさらに研究を重ね
た結果、Ni酸化物・Ni水酸物を鋼板表面に適正
密度で分散付着せしめた場合は、リン酸塩処理に
おいてリン酸塩皮膜結晶核の形成効果は金属Ni
付着にくらべて同等以上の作用を示すとともに、
冷延鋼板表面とのミクロセル形成効果が金属Ni
にくらべて稍々鈍感となる。従つて化成処理液に
組成変動があつても、これが敏感に化成処理反応
に反映して過度な反応速度を起すような事態にな
らずに済み、実用化成処理量産ラインで安定して
緻密な柱状フオスフオフエライト結晶を有する塗
装耐食性にすぐれた冷延鋼板表面が得られるとい
う新しい事実を知見した。
本発明は上記知見に基いてなされたものであつ
て、その要旨するところは、少くとも片面にNi
酸化物およびまたはNi水酸化物が、Ni元素重量
換算で、１〜150mg／m2付着していることを特徴
とする化成処理性にすぐれた表面処理鋼板にあ
る。
次にNi酸化物・Ni水酸化物の付着方法につい
て説明する。
付着方法としては、化学メツキ、電気メツキ、
蒸着後酸化処理、気相メツキ等のいずれの方法を
用いてもよく、特に限定するものではない。例え
ば電気メツキ法の一例を示せば次の通りである。
下記の浴組成からなるワツト浴に、
浴組成：NiSO4・6H2O 150ｇ／
NiCl2・6H2O 20ｇ／
H3BO3 15ｇ／
酸化剤としてH2O2、NO− ２有機系浴安定剤等を適
量添加して鋼板を電解処理すればよい。
次に本発明における各要件の限定理由を説明す
る。
Ni酸化物およびまたはNi水酸化物の付着量
を、Ni元素重量換算で、１〜150mg／m2としたの
は、１mg／m2未満ではミクロセル形成密度が不十
分で塗装耐食性の改善効果が不十分となるからで
ある。また150mg／m2を越えると、Ni酸化物・Ni
水酸物による被覆率が過大となつて化成処理反応
に適した（カソード）（アノード）面積比率が得
られなくなり、むしろリン酸塩結晶生成を抑制
し、皮膜にスケ（付着量不足）、脊抜き等の化成
ムラが発生するので好ましくないからである。
またNi酸化物、Ni水酸化物としてはそれぞれ
の各種単体もしくは双方が結合しているもの、お
よびそれらにさらに水分子が結合して水和したも
ののいずれでも差し支えない。
なお、本発明に基く化成処理性にすぐれた表面
処理鋼板の構造は、常に鋼板の両面に対して適用
しなければならないというものでなく、片面につ
いてのみこの構造を採用し他側の面は例えば異な
る構造のメツキ面とする形で実施するのも何等差
し支えない。こうした鋼板も、本発明の表面処理
鋼板の範畴に属するものである。
次に実施例を掲げて本発明の効果を説明する。
アルミキルド連続鋳造鋳片を素材として厚さ0.8
mmに冷間圧延した後、連続焼鈍ラインで焼鈍し、
気水冷却（N2＋水）で室温まで冷却しした後0.5
％圧下率で調質圧延し、さらに酸洗工程を経たア
ルミキルド冷延鋼板を用いて、第１表に示す基本
浴組成に安定化添加剤を少量加えて電気メツキに
よりNi酸化物・Ni水酸化物を前記鋼板表面に本
発明範囲で付着量を種々に変えて付着させ、本発
明例の供試材(C)〜(H)を得た。
The present invention relates to a surface-treated steel sheet with excellent chemical conversion treatment properties. During actual use, automotive steel sheets are generally processed by press forming, etc., and then subjected to chemical conversion treatment (for example, phosphate treatment) as a base treatment for paint.
Thereafter, for example, a cationic electrodeposition coating is applied to the coating for final use, but in order for the electrodeposition coating to have good paint corrosion resistance, it is first necessary to obtain a good chemical conversion coating in the base treatment. is an essential condition. In order to obtain this good chemical conversion coating, the surface of the cold-rolled steel sheet used as the raw material must have good properties (properties with excellent chemical conversion treatment properties) that do not inhibit the nucleation and growth of chemical conversion coating crystals. It becomes necessary. Now, cold-rolled steel sheets used as steel sheets for automobiles have conventionally been cooled after continuous annealing by methods such as gas jet cooling in a non-oxidizing atmosphere, so Mn, which is advantageous for forming a chemical conversion film, has been cooled. It was a steel sheet with excellent chemical conversion treatment properties, as it had a surface concentration layer such as iron hydroxide, etc., and there was no adhesion of corrosion products such as iron hydroxide. However, recently, in order to rationalize the heat cycle in the continuous annealing described above, there is a tendency to adopt water cooling or air/water cooling instead of gas jet cooling in a non-oxidizing atmosphere. In this case, since the cooling process creates an oxidizing atmosphere, an oxide film is formed on the surface, and therefore, for example, pickling treatment is required to remove this oxide film. The steel plate subjected to this pickling treatment has the above-mentioned Mn concentration layer removed,
In addition, pickling residue (iron hydroxide) is adsorbed on the surface, water rust occurs, etc., resulting in deterioration of surface quality and deterioration of chemical conversion treatment properties. In addition, when cold-rolled steel sheets are used for automobile bodies, etc., body corrosion becomes a safety issue, but recently, only one side of the automobile exterior panel, which is subject to severe corrosion, is coated with a highly corrosion-resistant plating, and the other side is left bare. Single-sided galvanized steel plates, which are designed to reduce car body corrosion by leaving the surface intact, have come into use. There are two manufacturing methods for single-sided plated steel sheets: electroplating and hot-dip plating. In the case of electroplating, pickling is performed as a pretreatment, and in many cases, an electroplating bath, which is an acidic bath, is used. Since it passes through and receives the pickling effect, the chemical conversion treatment property of the cold rolled steel sheet on the non-plated surface deteriorates. In addition, in the case of the hot plating method, it is difficult to avoid oxidation of the non-plated surface because it comes out from the hot melt plating bath into the atmosphere, and for this reason, pickling treatment is required after the plating is completed, and the same as above, the non-plated surface is exposed to the atmosphere. The chemical conversion treatment property of the surface deteriorates. Especially in recent years
Electroplating of Fe-based or Fe-Zn-based alloys is becoming more common, but in this case, the acidic plating bath contains a large amount of Fe 3+ ions, so the unplated surface is exposed to acid burns due to immersion in the plating bath. It exhibits a pitting state, and its chemical conversion treatment properties are extremely poor. There is also an electric Zn plating method, but in this case as well, highly corrosive chloride baths are used as the trend toward high current density operation progresses, and extremely severe dissolution occurs on the non-plated side, resulting in chemical conversion treatment. Sexuality has become extremely poor. In addition, especially when a vertical plating tank with a long immersion time is used, the deterioration of the chemical conversion treatment property of the non-plated surface will be much more severe than when using a horizontal plating tank, resulting in a serious situation. This has led to the occurrence of In recent years, the usage ratio of high-strength cold-rolled steel sheets has been increasing in the automobile and home appliance industries.
This is a problem because chemical conversion treatment properties are even worse when immersed in an acidic solution compared to general cold-rolled steel sheets. On the other hand, when applying chemical conversion treatment to steel sheets for automobiles, it is customary to form the raw steel sheet at the automobile manufacturer's side as described above and then apply chemical conversion treatment on a chemical conversion treatment mass production line.In this case, for example, zinc phosphate The bath components (Zn 2+ , Fe 2+ , nitrates, nitrites, chlorates, and other oxidation promoters) in the treatment solution change over time, and problems that deviate from the narrow range of bath management conditions tend to occur frequently. There has been a demand for a cold-rolled steel sheet that is highly responsive to changes in bath composition and can always maintain excellent chemical conversion properties. The present invention provides chemical conversion treatment properties that do not deteriorate on the pickled cold-rolled steel sheet surface and the non-plated surface of the single-sided plated steel sheet, and provide chemical conversion treatment properties that are highly responsive to changes in bath composition in mass production lines for chemical conversion treatment. The purpose is to provide a surface-treated steel sheet that can In order to improve the surface of cold-rolled steel sheets, which have poor chemical conversion properties, 0.3 to 0.3~
A method for depositing 10 mg/dm 2 is disclosed in JP-A-56-116883. According to the present invention, in a phosphate treatment test under stable treatment conditions, the effect of improving chemical conversion treatment properties (crystal size, adhesion amount, etc. of the chemical conversion film) and coating corrosion resistance can certainly be obtained. However, on the surface of a cold-rolled steel sheet to which metallic Ni has been deposited, the local battery formation effect of the metallic Ni precipitated on the surface is extremely strong.
The surface condition is extremely sensitive to chemical conversion reactions. As mentioned above, during the chemical conversion treatment on the zinc phosphate treatment mass production line, changes in the bath components over time are likely to occur, but since the amount of oxidation promoter added and the amount of metallic Ni deposited in the bath components are extremely small, these changes may occur. The rate of change in the amount of is likely to be particularly large.
Therefore, changes in these amounts are sensitively reflected in the chemical conversion reaction of cold-rolled steel sheets to which metallic Ni is attached, and when these amounts increase, the chemical conversion reaction rate (speed of chemical conversion film formation) becomes excessive, and the chemical conversion Many coarse acicular crystals of haupite, which have a negative effect on paint corrosion resistance, tend to form in the film. As is well known, the chemical conversion film in zinc phosphate treatment is composed of a composite zinc phosphate film consisting of hopite crystals and phosphofluorite crystals (dense columnar crystals), and as the number of hopite crystals increases, the corrosion resistance of the coating deteriorates. Therefore, cold-rolled steel sheets to which metallic Ni is attached are too sensitive and are not necessarily suitable for practical use such as chemical conversion treatment mass production lines. Therefore, the present inventors have developed a chemical conversion treatment material that has the property of not only providing good chemical conversion treatment properties but also preventing the chemical conversion reaction from being as sensitive to changes over time in the chemical conversion bath components as is the case with metallic Ni. With the intention of developing a surface-treated steel sheet with excellent surface treatment, we first considered a cold-rolled steel sheet with semiconducting properties such as Ni oxide and Ni hydroxide, which are less sensitive than metal Ni, attached to the surface. Various experimental studies were conducted. The present inventors developed an aluminum-killed cold-rolled steel sheet, which is a standard material for surface-treated steel sheets with excellent chemical conversion properties, which is an aluminium-killed cold-rolled steel sheet that has been subjected to a temper rolling process at a reduction rate of 0.5% after cooling after annealing in a non-oxidizing gas atmosphere. Ni oxide/Ni hydroxide is added to the cold rolled steel sheet, which has been pickled, washed with water, and then dried to deteriorate its chemical conversion properties.
Test material (D) with 30 mg/m 2 deposited in terms of Ni element weight.
I got it. For comparison, the standard cold-rolled steel sheet above
(A), cold-rolled steel plate (B) obtained by pickling the standard rolled steel plate (A), steel plate with 15 mg/m 2 of metallic Ni deposited on the cold-rolled steel plate (B)
(C) was used as the test material. The above test materials (A), (B), (C), and (D) were immersed in a zinc phosphate treatment solution (Bonderite 3030) for various immersion times to determine the amount of phosphate adhesion and the chemical conversion reaction rate (chemical conversion reaction rate). The time required to complete the treatment film formation was investigated. The results are shown in Figure 1. FIG. 1 is a diagram showing the relationship between the chemical conversion reaction time and the amount of phosphate deposited on the above-mentioned test materials (A), (B), (C), and (D). As shown in the figure, the formation of the chemical conversion film was approximately completed in about 2 minutes for all test materials (A), (C), and (D), indicating that they have excellent chemical conversion treatment properties; Material (B) was shown to have poor chemical conversion treatment properties. Regarding the chemical conversion reaction rate, sample material (C) was the fastest, sample material (D) showed almost the same chemical conversion rate as sample material (A), and compared to sample material (B). A remarkable improvement in chemical conversion treatment properties was shown. In addition, regarding the sensitivity of chemical conversion reactions,
For (C), when the amount of metallic Ni attached increases, the chemical conversion reaction rate quickly becomes excessive, and many coarse needle-like crystals with a high content of hopite are formed in the chemical crystals. ), the chemical conversion reaction rate showed almost no change even if the amount of Ni oxide/Ni hydroxide deposited increased, and dense crystals with a high content of phosphoophoreite were obtained. The response was far less sensitive. As a result of further research based on these research results, we found that when Ni oxide/Ni hydroxide is dispersed and adhered to the steel sheet surface at an appropriate density, the formation of phosphate film crystal nuclei during phosphate treatment is effective. is metal Ni
In addition to showing the same or better effect than adhesion,
The microcell formation effect with the cold rolled steel sheet surface is
It's a little less sensitive than that. Therefore, even if there is a compositional change in the chemical conversion treatment solution, this will not be sensitively reflected in the chemical conversion reaction and cause an excessive reaction rate. A new fact has been discovered that it is possible to obtain a cold-rolled steel sheet surface with excellent coating corrosion resistance that has phosphoophoreite crystals. The present invention has been made based on the above findings, and the gist thereof is that at least one side is made of Ni.
A surface-treated steel sheet with excellent chemical conversion treatment properties is characterized in that oxides and/or Ni hydroxides are adhered in an amount of 1 to 150 mg/m 2 in terms of Ni element weight. Next, a method for depositing Ni oxide/Ni hydroxide will be explained. Adhesion methods include chemical plating, electric plating,
Any method such as post-deposition oxidation treatment or vapor phase plating may be used, and is not particularly limited. For example, an example of the electroplating method is as follows. Bath composition: NiSO 4 6H 2 O 150g / NiCl 2 6H 2 O 20g / H 3 BO 3 15g / H 2 O 2 and NO - 2 as oxidizing agents to stabilize the organic bath. The steel plate may be subjected to electrolytic treatment by adding an appropriate amount of the agent or the like. Next, the reasons for limiting each requirement in the present invention will be explained. The adhesion amount of Ni oxide and/or Ni hydroxide is set to 1 to 150 mg/m 2 in terms of Ni element weight.If it is less than 1 mg/m 2 , the density of microcell formation is insufficient and the effect of improving paint corrosion resistance is reduced. This is because it will be insufficient. Moreover, if it exceeds 150mg/ m2 , Ni oxide/Ni
If the coverage rate of hydroxide becomes excessive, it becomes impossible to obtain the (cathode) (anode) area ratio suitable for the chemical conversion reaction, and it actually suppresses the formation of phosphate crystals, causing the film to become sagged (insufficient amount of adhesion), and to cause backbone. This is because it is undesirable because it causes formation unevenness such as removal. Further, the Ni oxide and Ni hydroxide may be either a single substance or a combination of both, or a hydrated product in which a water molecule is further bound to the Ni oxide and Ni hydroxide. Note that the structure of the surface-treated steel sheet with excellent chemical conversion properties according to the present invention does not always have to be applied to both sides of the steel sheet, but this structure is applied only to one side and the other side is applied, for example. There is no problem in implementing it with a plated surface of a different structure. Such steel sheets also belong to the scope of the surface-treated steel sheets of the present invention. Next, the effects of the present invention will be explained with reference to Examples.
Thickness 0.8 made from aluminum killed continuous casting slab.
After cold rolling to mm, annealing on continuous annealing line,
0.5 after cooling to room temperature with air-water cooling (N 2 + water)
Using an aluminium-killed cold-rolled steel sheet that has been temper-rolled at a rolling reduction of 1.5% and then subjected to a pickling process, a small amount of stabilizing additives are added to the basic bath composition shown in Table 1, and Ni oxide and Ni hydroxide are formed by electroplating. Sample materials (C) to (H) of examples of the present invention were obtained by depositing the substances on the surface of the steel plate in various amounts within the range of the present invention.
【表】
また比較のため、同様に酸洗工程を経たアルミ
キルド冷延鋼板に、同様のメツキ浴を用いて本発
明から外れた範囲でNi酸化物・Ni水酸化物を付
着せしめて比較例の供試材(A)(B)(I)(J)を得た。ひき
つづいてこれらの供試材(A)〜(J)を第２表に示す条
件でリン酸塩処理およびカチオン電着塗装を施し
た後、化成処理性および塗装耐食性を調査した。[Table] For comparison, Ni oxide and Ni hydroxide were applied to an aluminium-killed cold-rolled steel sheet that had undergone the same pickling process using the same plating bath to the extent that it was outside the scope of the present invention. Test materials (A), (B), (I), and (J) were obtained. Subsequently, these test materials (A) to (J) were subjected to phosphate treatment and cationic electrodeposition coating under the conditions shown in Table 2, and then chemical conversion treatment properties and coating corrosion resistance were investigated.
【表】
なお化成処理性については次の(イ)〜(ハ)により評
価した。
(イ) 化成皮膜のフオスフオフエライト（Ｐ）とホ
ーパイト(H)との比Ｐ／Ｐ＋ＨをＸ線回折から求
めた。
(ロ) 走査型電子顕微鏡により結晶の大きさを求め
た。
(ハ) 化成皮膜の付着量を重量法により求めた。
また塗装耐食性については、電着塗膜に２mm間
隔でゴバン目状に切れ目を入れたクロスカツト部
の塩水噴霧試験960時間後のセロテープ剥離巾で
評価した。
上記結果をまとめて第３表に示す。[Table] The chemical conversion treatment property was evaluated using the following (a) to (c). (a) The ratio P/P+H of phosphorous ophthalite (P) and hopite (H) in the chemical conversion coating was determined from X-ray diffraction. (b) The size of the crystal was determined using a scanning electron microscope. (c) The amount of chemical conversion film deposited was determined by gravimetric method. The corrosion resistance of the coating was evaluated by measuring the peeling width of the cellophane tape after 960 hours of a salt spray test on a cross-cut area in which cuts were made in a gong shape at 2 mm intervals in the electrodeposited coating. The above results are summarized in Table 3.
【表】【table】
【表】
第３表に見る通り、比較例(A)(B)はＰ／Ｐ＋Ｈが
100で良好、皮膜付着量も十分であつたが、Ni酸
化物・Ni水酸化物の付着量が0.05mg／m2と過少で
あるためミクロセル形成密度が不十分で結晶が粗
大となり、皮膜にムラ・スケが多発し化成処理性
が不良で、かつ塗膜剥離巾も大で塗装耐食性も不
良であつた。また比較例(I)(J)はNi酸化物・Ni水
酸化物の付着量が過多で、これらの被覆率が過大
のため、リン酸塩結晶の生成が抑制されて化成皮
膜付着量が僅少となり、化成皮膜にスケが発生し
化成処理性が不良で、かつ塗膜剥離巾も大で塗装
耐食性も不良であつた。これに対し、本発明例(C)
〜(H)はいずれもＰ／Ｐ＋Ｈが100％で良好、化成
皮膜付着量が適正、結晶の大きさも微細緻密であ
り、ムラ・スケの発生もなく良好な化成処理性を
示すとともに、塗膜剥離巾も1.0mm以下と極めて
良好な塗装耐食性を示した。
以上述べた如く本発明の表面処理鋼板は、酸洗
工程を経ないで製造された従来の冷延鋼板なみの
すぐれた化成処理性を有するとともに、化成処理
後のカチオン電着塗装において塗装耐食性の良好
な塗膜の形成を可能とする許りでなく、実用化成
処理ラインにおける化成処理液の組成変動に対し
て過度な反応加速を示さず安定して良好な化成結
晶を形成し得るという有利性を備えているので、
従つて自動車用鋼板として極めて実用価値の高い
鋼板といえる。[Table] As shown in Table 3, in comparative examples (A) and (B), P/P+H is
100 was good and the amount of film adhesion was sufficient, but because the amount of Ni oxide/Ni hydroxide adhesion was too small at 0.05mg/ m2 , the density of microcell formation was insufficient and the crystals became coarse, causing problems in the film. There were many unevenness and scratches, and the chemical conversion treatment property was poor.The peeling width of the paint film was also large, and the paint corrosion resistance was also poor. In addition, in Comparative Examples (I) and (J), the amount of Ni oxide and Ni hydroxide deposited was excessive, and the coverage ratio of these was excessive, so the formation of phosphate crystals was suppressed and the amount of chemical conversion coating deposited was small. As a result, scattering occurred in the chemical conversion coating, resulting in poor chemical conversion treatment properties, and the peeling width of the coating was large, resulting in poor paint corrosion resistance. In contrast, the present invention example (C)
- (H) are all good with P/P+H of 100%, the amount of chemical conversion coating is appropriate, the crystal size is fine and dense, and there is no unevenness or scratching, showing good chemical conversion treatment properties, and the coating film is The peeling width was less than 1.0mm, showing extremely good paint corrosion resistance. As described above, the surface-treated steel sheet of the present invention has excellent chemical conversion treatment properties comparable to conventional cold-rolled steel sheets manufactured without going through a pickling process, and also has excellent paint corrosion resistance in cationic electrodeposition coating after chemical conversion treatment. Not only does it enable the formation of a good coating film, but it also has the advantage of being able to stably form good chemical crystals without excessively accelerating the reaction in response to changes in the composition of the chemical conversion treatment liquid in practical chemical conversion treatment lines. Since it is equipped with
Therefore, it can be said that this steel sheet has extremely high practical value as a steel sheet for automobiles.
第１図は化成反応時間とリン酸塩付着量の関係
を示した図である。
FIG. 1 is a diagram showing the relationship between the chemical conversion reaction time and the amount of phosphate deposited.
Claims (1)
水酸化物が、Ni元素重量換算で１〜150mg／m2付
着していることを特徴とする化成処理性にすぐれ
た表面処理鋼板。1 Ni oxide and or Ni on at least one side
A surface-treated steel sheet with excellent chemical conversion treatment properties, characterized in that hydroxide is adhered at 1 to 150 mg/m 2 in terms of Ni element weight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3505083A JPS59159987A (en) | 1983-03-02 | 1983-03-02 | Surface-treated steel sheet with superior suitability to chemical conversion treatment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3505083A JPS59159987A (en) | 1983-03-02 | 1983-03-02 | Surface-treated steel sheet with superior suitability to chemical conversion treatment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59159987A JPS59159987A (en) | 1984-09-10 |
| JPS6229510B2 true JPS6229510B2 (en) | 1987-06-26 |
Family
ID=12431206
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3505083A Granted JPS59159987A (en) | 1983-03-02 | 1983-03-02 | Surface-treated steel sheet with superior suitability to chemical conversion treatment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59159987A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3292230B1 (en) | 2015-05-07 | 2019-06-12 | Phosfan Ltd. | Method for applying ultrafine phosphate conversion crystal coatings |
| WO2017077514A1 (en) * | 2015-11-05 | 2017-05-11 | Phosfan Ltd. | Composite phosphate coatings |
-
1983
- 1983-03-02 JP JP3505083A patent/JPS59159987A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59159987A (en) | 1984-09-10 |
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