Dengiz bronza qoplamalarining amaliy kavitatsion eroziya sinovi

Kavitatsiya eroziyasini sinash eng foydali bo‘lgani shu paytda bo‘ladi, agar u nazorat qilingan laboratoriya ta'sirini haqiqiy muhandislik muammosi bilan bog‘lasa. Amaliy misol sifatida kemaning rul va pervanelar kabi dengiz komponentlari uchun kavitatsiyaga chidamli bronza qoplamalarni baholashni keltirish mumkin. Ushbu qismlar mahalliy bosim o‘zgarishlari bug‘ pufakchalarini yuzada portlashi mumkin bo‘lgan hududlarda ishlaydi va bu takroriy yuqori intensivlikdagi zarba yuklarini hosil qiladi. Vaqt o'tishi bilan bu pitting, charchash shikastlanishi, qoplamaning shikastlanishi va material yo‘qolishiga olib keladi.

Bronza qoplamalarning kavitatsiya eroziyasi sinovi

Hauer va boshq. tomonidan o'tkazilgan tadqiqotda, sovuq purkash, issiq purkagich, HVOF purkash va ark purkash orqali hosil bo'lgan bronza qoplamalar quyma nikel alyuminiy bronza va kemasozlik po'lati bilan solishtirildi. Asosiy savol oddiy edi: qaysi qoplama jarayoni bronza yuzasini kavitatsiya ta'sirida dengizda xizmat qilish uchun yetarlicha uzoq vaqt bardosh bera oladi? Bunga javob berish uchun tadqiqotchilar ASTM G32-16 asosidagi kavitatsiya eroziya testidan foydalanib, vibratsion apparat bilan jihozlangan va sinov tizimi sifatida Hielscher UIP1000hdT ultratovushli vibratsiya tizimini o'z ichiga olgan.

Test sharoitlarini aniq nazorat qilish va avtomatlashtirilgan ma'lumotlarni yozib olish

The sonicator UIP1000hdT is well suited for this type of test because it delivers high-intensity, low-frequency ultrasound in the range used for cavitation erosion testing. The cavitation erosion test setup using the 1000-watt sonicator operates at 20 kHz, and allows for precise process monitoring, amplitude control, temperature measurement, and automatic protocoling of test data. These functions are important because cavitation intensity depends strongly on amplitude, liquid temperature, liquid pressure, sonotrode geometry, and the distance between the sonotrode and specimen.

(a) ASTM G32-16 bo'yicha kavitatsiya eroziyasi testi UIP1000hd sonikatori bilan (bilvosita usul). Barcha test parametrlari nominal qiymatlardir; toleranslar standartda keltirilgan.
(b) Eroziya-vaqt egri chizig'idagi sxematik fazalar va test jarayonidagi xarakteristik parametrlar.
Grafikalar va tadqiqot: ©Hauer va boshq., 2021.

Bronza qoplamalarining ultratovush kavitatsiya eroziyasi sinovi

For the marine bronze coating example, the test was performed in the indirect ASTM G32 arrangement. In this configuration, the specimen is not attached to the vibrating horn. Instead, the ultrasonic sonotrode generates cavitation in distilled water, and the coated specimen is fixed beneath the sonotrode at a defined gap. Hauer et al. used a 0.5 mm distance between sample and sonotrode, a frequency of 20 kHz, and a peak-to-peak amplitude of 50 µm. The test liquid was distilled water, held at approximately room temperature, around 25 °C.

Namuna tayyorlash muhim bosqich. Kavitatsiya ta'siridan oldin, qoplangan yuzalar bosqichma-bosqich maydalanib, 4 μm dan pastda mayda olmos abraziv darajasiga silliqlangan. Bu bo'sh biriktirilgan zarralar yoki yuzaki notekisliklarning ta'sirini kamaytiradi, aks holda ular darhol ajralib, eroziya egri chizig'ini buzishi mumkin. Maqsad qoplamani chiroyli ko'rsatish emas, balki takrorlanadigan boshlang'ich sharoit yaratishdir, shunda o'lchangan massa yo'qotilishi kavitatsiya qarshiligini aks ettiradi, sirtning yomon tayyorlanishi emas.

Ultrasonik kavitatsiya eroziyasini sinovdan o'tkazish tartibi va uning natijalari

The practical test procedure is straightforward. First, each specimen is cleaned, dried, and weighed on a precision balance. It is then mounted in the test cell beneath the sonotrode BS4d22 of the sonicator UIP1000hdT with the 0.5 mm gap set carefully and repeatably. The sonicator is operated at the defined amplitude and frequency, while the liquid temperature is controlled to prevent heating from changing cavitation intensity. After a defined exposure interval, the specimen is removed, cleaned, dried, and weighed again. This sequence is repeated over increasing, material-dependent exposure intervals until a complete erosion curve is obtained.
The raw measurement is mass loss. For engineering comparison, this mass loss is converted into volume loss using the material density. The volume loss is then divided by the exposed surface area to determine mean erosion depth. From the erosion-depth curve, the researcher can calculate characteristic erosion parameters such as maximum erosion rate, terminal erosion rate, and mean depth of erosion. Hielscher also notes that erosion can be reported as mass, volume, or penetration depth per time or per delivered ultrasonic energy, depending on the chosen protocol.

O'rtacha eroziya chuqurliklari, sozlangan qoplama sifat parametrlari funksiyasi n. Kukun annealizatsiyasi va shu bilan kamaygan kukun mustahkamligi yuqori qoplama sifatiga erishish imkonini beradi. Insertlar 100 daqiqalik kavitatsiya sinovidan so'ng yuzaga kelgan sirt shikastlanishini ko'rsatadi.
Grafiklar va tadqiqot: ©Hauer va boshq., 2021.

One important lesson from the Hauer study is that early erosion rates can be misleading. Thermally and kinetically sprayed coatings often showed high initial material loss, followed by a lower, more stable erosion rate. For this reason, Hauer et al. used terminal erosion rate as a more representative indicator of long-term coating performance. In their 120-minute comparison, the terminal erosion rate was evaluated mainly from the second half of the test, above 60 minutes, to better capture the stabilized behavior.

The test results show why a controlled vibratory cavitation apparatus is valuable. Cast nickel aluminum bronze achieved a terminal erosion rate of about 0.40 µm/h. Optimized warm-sprayed bronze reached 0.57 µm/h, close to the cast reference. An optimized arc-sprayed coating on shipbuilding steel reached about 1.02 µm/h, while an optimized HVOF coating reached about 1.74 µm/h. Even when these coatings did not fully match cast propeller bronze, they dramatically outperformed shipbuilding steel; the study reports that arc-sprayed and HVOF-sprayed coatings achieved about 26 times and 16 times better cavitation resistance, respectively, than VL-A steel.

Use a Sonicator as Vibratory Apparatus for Your Cavitation Erosion Tests

The practical conclusion is that cavitation erosion testing with the UIP1000hdT sonicator as vibratory apparatus can do more than rank materials. It reveals how coating process, microstructure, oxide content, porosity, interface bonding, and post-treatment affect real erosion behavior. Hauer et al. concluded that HVOF and arc spraying can offer a strong performance-cost compromise for improving steel rudder surfaces, while cold and warm spraying are preferred when cavitation resistance close to bulk nickel aluminum bronze is required.

Laboratoriyalar va qoplama ishlab chiqaruvchilari uchun takrorlanadigan natijalar uchun kalit test parametrlarini qat'iy nazorat qilishdir: sonotrod amplitudasi, chastota, sonotroddan namunaga masofa, suyuqlik harorati, suyuqlik kimyosi, namuna tayyorlash, tortish intervallari va eroziya tezligini hisoblash. Ushbu shartlar belgilanganidan so'ng, Hielscher UIP1000hdT ultratovush kavitatsiyasini miqdoriy qoplama samaradorligi ma'lumotlariga tarjima qilishning amaliy va takrorlanadigan usulini taqdim etadi.

Kavitatsiya eroziyasini tekshirish uchun namunaviy ish varag'i

 
Kavitatsiya eroziyasi testlari bo'yicha ko'rsatmalarni bu yerdan topishingiz mumkin!

ASTM G32 Kavitatsiya Eroziyasi Sinov Sozlamasi

UIP500hdT, UIP1000hdT, UIP15000hdT va UIP2000hdT sonikatorlari ASTM G32 sinovlari uchun mos keladi. Biz har bir bo'linmaga aniq ma'lumot bera olamiz amplitudani o'lchash protokoli sonotrod uchidagi mexanik amplitudani. Biz ushbu qurilmalardan birini sonotrode BS4d22 (diametri 22 mm) va ST2 stendi bilan ishlatishni tavsiya qilamiz.

ASTM G32 -16 almashtiriladigan uchi bilan 15,9 mm Sonotrode

Dizayn, ishlab chiqarish va konsalting – Germaniyada ishlab chiqarilgan sifat

Hielscher ultrasonikatorlari eng yuqori sifat va dizayn standartlari bilan mashhur. Mustahkamlik va qulay foydalanish ultratovush qurilmalarimizni sanoat ob'ektlariga silliq integratsiya qilish imkonini beradi. Qo'pol sharoitlar va talabchan muhit Hielscher ultrasonikatorlari tomonidan osonlik bilan hal qilinadi.

Hielscher Ultrasonics ISO sertifikatiga ega kompaniya bo'lib, eng zamonaviy texnologiya va foydalanuvchilarga qulaylik bilan ajralib turadigan yuqori samarali ultratovush apparatlariga alohida e'tibor beradi. Albatta, Hielscher ultrasonikatorlari Idoralar talablariga javob beradi va UL, CSA va RoHs talablariga javob beradi.

Adabiyot / Adabiyotlar